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A 75-day rearing trial was completed to investigate the effectiveness of different biofloc systems (BFT) on the water quality, growth performance and health status of Florida red tilapia (FRT) grown in brackish groundwater (BGW). The trial consisted of the control and three types of BFT using different carbon sources (CS), starch (ST), rice bran (RB), and wheat bran (WB) in triplicate, expressed as BF-0, BF-ST, BF-RB, and BF-WB, respectively. Fish weighing 4.98 ± 0.01 g/fish were stocked in 250-L tanks at an initial stocking density of 25 fish. The findings demonstrated significant reductions in inorganic nitrogen by-product (NH3 and NO2) levels in all BFT groups compared to the control, with an increase in floc volume and floc nutritional value, in the BF-ST and BF-RB groups. Furthermore, fish in the BF-ST and BF-RB groups showed significant improvements in fish growth indices (final weight, weight gain, and FCR). Fish in the BFT groups showed significant improvement in kidney function indices and plasma lipids with no significant changes in liver enzyme activity compared to the control. Lower stress markers (glucose and cortisol) and higher digestive enzyme activity (lipase and protease), innate immune parameters and antioxidants were reported in fish of the BF-ST and BF-RB groups compared to the control fish. Histopathological inspection revealed that the BF-ST fish exhibited healthier livers and shared healthier intestines with BF-RB fish compared to the control group. In conclusion, RB is an appropriate CS with BGW for desert aquaculture due to its availability, inexpensiveness, and comparable outcomes with ST. [ABSTRACT FROM AUTHOR]

This study explored the effects of mango seed (MS) powder supplementation on the growth, immune response, gene expression, and intestinal morphology of Nile tilapia (Oreochromis niloticus) over an 8-week period. A total of 300 Nile tilapia fingerlings (average weight of 15.29 ± 0.05 g) were divided into five treatment groups and fed either a basal diet or one of four experimental diets containing MS powder at concentrations of 10 (MS10), 20 (MS20), 40 (MS40), and 80 (MS80) g kg−1. The results demonstrated that Nile tilapia fed MS-supplemented diets experienced significant improvements (p < 0.05) in weight gain (WG), specific growth rate (SGR), and survival rate (SR) compared to the control group (0 g kg−1 MS). The MS-treated groups also showed a significant increase (p < 0.05) in the height and branching of intestinal villi along the entire length of the intestine, as well as a significantly higher villus-to-crypt depth ratio (V/C), indicating enhanced intestinal health and functionality. Moreover, although MS supplementation did not increase peroxidase activity, it did lead to a significant increase (p < 0.05) in the activity of skin mucus and serum lysozyme, along with upregulated gene expression of immune-related (IL-1, IL-8, and LBP) and antioxidant genes (GST-α, GPX, and GSR). Polynomial regression analysis identified an optimal MS dosage of 36.43–45 g kg−1 for effectively improving growth, immunity, and immuno-oxidant gene expression in Nile tilapia. These results emphasize mango seed (MS) as a promising natural supplement for improving the diet of Nile tilapia and, potentially, other freshwater fish widely used in aquaculture. [ABSTRACT FROM AUTHOR]

Abstract Background The biofloc system (BFS) provides a sustainable aquaculture system through its efficient in situ water quality maintenance by the microbial biomass, besides continuous availability of these protein-rich microbes as feed to enhance growth and immunity of the reared organism. This study explores the gill architecture, growth performance, digestive enzyme activity, intestinal microbial composition, and histology of three freshwater fish species, Puntius gonionotus, Pangasianodon hypophthalmus, and Heteropneustus fossilis reared in biofloc based polyculture system. Results The three species in T2 showed significantly higher WG and SGR, followed by T1 and T3. The wet mount of gill architecture showed smaller inter-filament gaps in gill arches of silver barb followed by stinging catfish and stripped catfish, but showed no correlation with the weight gain. However, silver barb being an omnivore and filter-feeder, accumulated a more diverse microbial community, both in T1 and BFS (T2 and T3), while the bottom feeder H. fossilis exhibited unique gut bacterial adaptability. The presence of floc in T2 and T3 enhanced bacterial abundance in water and fish gut, but their microbial diversities significantly reduced compared to T1 receiving only feed. Next-generation sequencing revealed that the Pseudomonas dominated in gut of P. gonionotus and P. hypophthalmus in T1, Enterobacterales and Fusobacterium prevailed in those of T2 and T3, respectively. In contrast, gut of H. fossilis had the highest proportion of Clostridium in T1, while Rhizobiaceae dominated in T3. Similarly in floc samples, Enterococcus dominated in T1 while Micrococcales and Rhizobiaceae dominated in T2 and T3, respectively. A positive correlation of enterobacteria, with the digestive enzyme activities and growth patterns was observed in all treatments. Conclusion The present study revealed feeding behaviour to play crucial role in distinguishing the gut microbial composition patterns in fishes reared in Biofloc System. Further it revealed the requirement of supplementary feed along with floc in these three species for higher growth in the biofloc system.

Background: The biofloc system (BFS) provides a sustainable aquaculture system through its efficient in situ water quality maintenance by the microbial biomass, besides continuous availability of these protein-rich microbes as feed to enhance growth and immunity of the reared organism. This study explores the gill architecture, growth performance, digestive enzyme activity, intestinal microbial composition, and histology of three freshwater fish species, Puntius gonionotus, Pangasianodon hypophthalmus, and Heteropneustus fossilis reared in biofloc based polyculture system. Results: The three species in T2 showed significantly higher WG and SGR, followed by T1 and T3. The wet mount of gill architecture showed smaller inter-filament gaps in gill arches of silver barb followed by stinging catfish and stripped catfish, but showed no correlation with the weight gain. However, silver barb being an omnivore and filter-feeder, accumulated a more diverse microbial community, both in T1 and BFS (T2 and T3), while the bottom feeder H. fossilis exhibited unique gut bacterial adaptability. The presence of floc in T2 and T3 enhanced bacterial abundance in water and fish gut, but their microbial diversities significantly reduced compared to T1 receiving only feed. Next-generation sequencing revealed that the Pseudomonas dominated in gut of P. gonionotus and P. hypophthalmus in T1, Enterobacterales and Fusobacterium prevailed in those of T2 and T3, respectively. In contrast, gut of H. fossilis had the highest proportion of Clostridium in T1, while Rhizobiaceae dominated in T3. Similarly in floc samples, Enterococcus dominated in T1 while Micrococcales and Rhizobiaceae dominated in T2 and T3, respectively. A positive correlation of enterobacteria, with the digestive enzyme activities and growth patterns was observed in all treatments. Conclusion: The present study revealed feeding behaviour to play crucial role in distinguishing the gut microbial composition patterns in fishes reared in Biofloc System. Further it revealed the requirement of supplementary feed along with floc in these three species for higher growth in the biofloc system. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of using different vegetable brans as organic carbon source in synbiotic system fertilization on the nitrification process, plankton composition, and growth of Penaeus vannamei in the nursery phase, also comparing it with the biofloc system. An extended nursery rearing was carried out for 53 days, at a density of 2000 shrimp m−3 (initial weight: 0.03 ± 0.01 g). The following treatments were established, with five repetitions: CW, clear water (control); BFT, biofloc system; RB, synbiotic system fertilized with rice bran; SB, synbiotic system fertilized with soybean bran; and WB, synbiotic system fertilized with wheat bran. The synbiotic fertilization protocol used a commercial blend of Bacillus subtilis and Bacillus licheniformis, molasses, sodium bicarbonate as buffer, and water. The fertilizers were processed by an anaerobic (24 h) and an aerobic (24 h) phase. BFT treatment used molasses as organic carbon source. At the end of the trial, final weight was higher in CW, BFT, and RB treatments than in WB. In RB, SB, and WB treatments, TAN was controlled between days 10 and 14 and NO2−-N was controlled from day 40 of the trial, resembling a newly started system. At the end of the trial, a higher abundance of coccoid and bacillus was observed in the RB treatment, while a higher abundance of vibrio bacteria was observed in WB. Rice bran proved to be the best alternative for the synbiotic fertilization, as it presented a final weight (3.27 g) similar to BFT and CW treatments, and higher than WB (2.61 g). Also, the use of rice bran produced a high load of microorganisms, which can improve shrimp growth. [ABSTRACT FROM AUTHOR]

The constant and significant growth of aquaculture activity necessitates the intensification of cultivation systems and develop more efficient, cost-effective and bioavailable diets. In this context, the use of alternative ingredients to fishmeal, such as fermented soybean meal (FSFM) and Spirulina biomass (Arthrospira platensis), should be considered. This review article aims to conduct a survey of studies with alternative ingredients to fishmeal for tilapia and other fish species, cultivated in more intensive farming systems, such as the biofloc system. Thus, it can be conclude that these ingredients allow the replacement (partial or total) of fishmeal in diets for Nile tilapia and other fish species. Furthermore, important information about the benefits arising from intensive systems, benefits that justify their use in the cultivation of these animals, were also observed. [ABSTRACT FROM AUTHOR]

Biofloc technology is instrumental in improving growth performance and yield in shellfish aquaculture, while leading to enhanced water quality through maintaining the nutrients level within a safe range. More specifically, toxic nitrogenous wastes are converted into beneficial microbial biomass known as "biofloc", contributing to improve shellfish immune system. Among the various parameters affecting the efficiency of the process is the carbon source and C:N ratio. In light of these, the present work critically reviews the effects of biofloc systems on growth performance, immunity and diseases resistance in shellfish production. Moreover, it scrutinizes the microbial diversity and nutritional composition of biofloc. Then, the application of the technology in various shellfish cultures, including shrimp, freshwater prawn, crabs, crayfish, clam, and oyster, is presented. Overall, biofloc systems contribute to enhanced shellfish survival rate to the highest value of 96–100% for marine shrimp, 95–99% for freshwater prawn, 70–83% for crayfish, 83–100% for oyster, Crassostrea sp. and up to 2% for mud crabs larvae through substantially reducing the ammonia level in the culture (summarized in Table 1 – Table 5). Finally, the main challenges in utilizing biofloc systems, i.e., suitable aeration and mixing and microbial mechanisms involved are also explained to shed light on future research directions in the field. [ABSTRACT FROM AUTHOR]

LED light source has the advantages of energy saving and environmental protection, high photoelectric conversion efficiency, which can meet the demand for green, efficient and intelligent development of factory farming. To investigate the effect of LED culture lights on the muscle quality of Litopenaeus vannamei in the biofloc system, two treatment groups were set up:the LED light group (L group) and the natural light group (N group). The culture experiments were conducted over an 8-week period, utilizing larvae L. vannamei as the study material. The larvae had a mean body length of 5. 23±0. 61 cm and a mean body mass of 1. 52± 0. 47 g. The illumination parameters of the L group were a mixture of blue- green light ( green light 545 nm, blue light 450 nm); the photoperiod was 15L ∶9D; the light intensity was 2 000 Lx. The experimental results showed that there were no significant differences in conventional nutrients (moisture, crude protein, crude fat, ash) between L group and N group ( P > 0. 05). A total of 18 amino acids were detected in muscle. The contents of threonine (Thr), tyrosine ( Tyr), arginine (Arg), glycine (Gly) and ∑EAA/ ∑NEAA in the muscles of the L group were significantly higher than those of the N group (P < 0. 05). There were no significant differences in the contents of essential amino acids (EAA), semi- essential amino acids (HEAA) and aromatic amino acids (DAA) (P>0. 05). A total of 37 fatty acids were found in muscle. The contents of C12:0, DHA and EPA+DHA in the muscle of shrimp from the L group were significantly higher than those from the N group (P<0. 05). The contents of C21:0, C20:3n-3, C20:3n-3 and C22:5n-6 were significantly lower than those in the N group (P<0. 05). The results indicate that the LED light parameter could improve the nutritional quality of the muscle of L. vannamei. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of the biofloc technology (BFT) system and the replacement of fish meal with Spirulina biomass on productive performance, intestinal histomorphometry, plasma biochemistry, and oxidative stress of Nile tilapia juveniles (Oreochromis niloticus) fed suboptimal levels of protein. Two factors were evaluated: production systems (clear water × BFT) and replacement of fish meal with Spirulina (0, 33, 66 e 100%). The design was in a 2 × 4 randomized factorial scheme with four replications, and the fish were evaluated for 48 days. Four isoproteic (28% crude protein) diets were formulated with gross energy values close to 4300 kcal kg−1. Nile tilapia juveniles (0.23 ± 0.01 g) were distributed in 16 circular tanks (70 L) at seven fish/tank. The diets were formulated with protein levels approximately 20% below that required for the species and life stage. No interaction was observed between the factors evaluated (production systems × Spirulina inclusion). Rearing the fish in the BFT system avoided the adverse effects of diets with suboptimal protein levels on performance, intestinal histomorphometry, and protein metabolism. Lower values lower lipid peroxidation and higher antioxidant capacity were observed in fish reared in the BFT system, showing evidence of improvements in antioxidant responses and lower levels of physiological oxidative stress. Spirulina completely replaced fish meal in the diets of Nile tilapia juveniles without adverse effects on intestinal morphometry, protein metabolism, and antioxidant response. Replacing 66% of fish meal with Spirulina improved the productive performance, regardless of the rearing system. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the bioflocculant chitosan and its nano-conjugated form in biofloc production and to evaluate the growth performance of genetically improved farmed tilapia (GIFT) in an insitu biofloc system. A completely randomised design (CRD) was used to evaluate the growth performance of GIFT in insitu biofloc over a 75-day period. The trial was conducted with biofloc control (T1), 30 ppm chitosan (T2) and 30 ppm nano-chitosan (T3) in triplicate. The water quality parameters were maintained in the optimum range for biofloc production. The highest value for flocculation activity, total suspended solids, total dissolved solids and total solids other than floc volume was observed in T3 followed by T2 and T1. The result of this study showed that there was a significant difference (p < 0.05) between treatments in terms of specific growth rate (SGR), weight gain (%WG), feed conversion ratio (FCR), feed efficiency ratio (FER) and daily increment (DI). Good growth performance of fish was observed in biofloc produced with nano-chitosan in terms of average body weight (g) (24.74 ± 2.58), SGR (%/day) (3.56 ± 0.094), PWG (%) (1546.27 ± 143.42), lowest FCR (1.421 ± 0.029), FER (0.62 ± 0.011), PER (1.68 ± 0.03) and DI (g day−1) (0.21 ± 0.014). The highest levels of amylase, lipase and protease activity and increased activity of antioxidant enzymes (SOD and CAT) were found in the T3 treatment compared to T2 and T1 treatments. This study demonstrated that biofloc developed with 30 ppm nano-chitosan could shorten the production time of biofloc, maintain the water quality of the biofloc system and improve the growth of GIFT tilapia reared in an insitu biofloc system with inland saline groundwater. [ABSTRACT FROM AUTHOR]

The study examined the impacts of varying protein levels and additional substrate area for periphyton formation on the growth and survival of whiteleg shrimp postlarvae reared in a biofloc system. Shrimp postlarvae were stocked in eighteen 100L tanks each filled with 60L of seawater (28 = salinity). In a 3×2 factorial arrangement, the experimental diets were formulated to contain three varying dietary protein levels (25, 35, and 45% CP). Shrimp diets were prepared and supplied during the subsequent interval of the trial. The dietary protein levels were subjected to study in combinations with two different levels of periphyton surface areas (no periphyton P0% and P100% tank surface area). Different dietary protein and substrate addition levels significantly influenced growth performance, feed utilization, and survival. The dietary protein level in the diets of shrimp postlarvae reared in the Biofloc system can be reduced from 45 to 35% CP without negative effects on growth and feed conversion response. Regardless of the dietary protein level, results indicated much greater benefits for adding periphyton substrate to the shrimp-rearing system. Survival ranged between 76.67 and 91.33% and increased significantly from 84.33 (without substrate) to 91.56% (100% additional substrate area) regardless of the dietary protein level. Irrespective of substrate levels, they were 83.667, 88.167, and 92.0% for 25, 35 and 45% of CP, respectively. Likewise, periphyton enhances the immunity gene expressions of L. vannamei. The artificial substrate has economic advantages and is easy to establish. Although the positive impact for white leg shrimp, there is no interaction between the percentages of protein levels and the presence of absent artificial substrate. [ABSTRACT FROM AUTHOR]

Abstract The aim of the present study was to evaluate the water quality, growth performance, body composition, length–weight relationship, condition factors and benefit–cost analysis of giant freshwater prawn (Macrobrachium rosenbergii) cultured with biofloc system in pond conditions. The experiment was conducted in twelve (12) experimental ponds, each measuring 240 m2. The control group was cultured without any biofloc (T1), and biofloc‐based three treatments were biofloc with 100% feed (T2), biofloc with 90% feed (T3) and biofloc with 80% feed (T4). The biofloc‐based treatments showed significantly higher floc volume, total suspended solids, total heterotrophic bacteria and plankton density than the control (p

Abstract Background Shrimp cultured in a biofloc system (BFS) have a lower disease incidence than those farmed in a water exchange system (WES). Although a number of studies have reported that the gut bacterial community induced by BFS is highly associated with shrimp disease resistance, the causal relationship remains unknown. Here, the promotive roles of gut bacterial community induced by BFS in pathogenic Vibrio infection resistance and its potential micro-ecological and physiological mechanisms were investigated by gut bacterial consortium transplantation and synthetic community (SynCom) construction. Results The BFS induced a more stable and resistant gut bacterial community, and significantly enriched some beneficial bacterial taxa, such as Paracoccus, Ruegeria, Microbacterium, Demequina, and Tenacibaculum. Transplantation of a gut bacterial consortium from BFS shrimp (EnrichBFS) greatly enhanced the stability of the bacterial community and resistance against pathogenic V. parahaemolyticus infection in WES shrimp, while transplantation of a gut bacterial consortium from WES shrimp significantly disrupted the bacterial community and increased pathogen susceptibility in both WES and BFS shrimp. The addition of EnrichBFS in shrimp postlarvae also improved the pathogen resistance through increasing the relative abundances of beneficial bacterial taxa and stability of bacterial community. The corresponding strains of five beneficial bacterial taxa enriched in BFS shrimp were isolated to construct a SynComBFS. The addition of SynComBFS could not only suppress disease development, but also improve shrimp growth, boost the digestive and immune activities, and restore health in diseased shrimp. Furthermore, the strains of SynComBFS well colonized shrimp gut to maintain a high stability of bacterial community. Conclusions Our study reveals an important role for native microbiota in protecting shrimp from bacterial pathogens and provides a micro-ecological regulation strategy towards the development of probiotics to ameliorate aquatic animal diseases. Video Abstract

Osphronemus gouramy is a potential Indonesian fish that needs to be supported by good nutritional feed and water quality in a culture system. The research on the effect of combining Chlorella vulgaris (C. vulgaris) supplementation with culture systems of biofloc and non-biofloc in gourami fish on amylase activity and blood urea level has not been conducted. Therefore, this study aims to determine the effect of C. vulgaris supplementation with different culture systems on the amylase activity of various digestive organs and blood urea levels. It obtains the best C. vulgaris supplementation feed combination to increase the amylase activity of various digestive organs and reduce blood urea levels. This research was carried out experimentally with a Factorial Completely Randomized Design consisting of two factors. Furthermore, gourami was fed with C. vulgaris levels of 0, 2, 3, 4, and 5 g kg-1 for 28 days and divided into biofloc and non-biofloc groups of culture systems. The amylase activity was measured at three pH buffers, and blood urea levels were analyzed using a urea kit. The results showed that amylase activity increased when supplemented with C. vulgaris 5 g kg-1 feed using the biofloc system, while blood urea levels decreased. C. vulgaris supplementation and biofloc system are alternative solutions to improving nutrition and water quality.

Especially in arid regions, developing tilapia culture with the ability to survive a wide range of salinities is crucial due to the limited availability of fresh water for aquaculture. The present study focused on evaluating the growth performance of Nile tilapia in a biofloc system under three salinity levels: 0 (BFT0), 4 (BFT4), and 8 g/L (BFT8). Fingerling fish were raised for 37 days in tanks with a water volume of 140 liters and a stocking density of one fish per liter. The results of the water quality parameters showed that dissolved oxygen and pH decreased with increasing salinity. Furthermore, the BFT8 group had the highest concentrations of settled solid (19.98 ml/L) and total suspended solid (428.37 mg/L), while the BFT8 group had the lowest TAN concentration (4.32 mg/L). The final weight and specific growth rate were significantly higher in the BFT8 and BFT4 groups compared to the BFT0 group. Survival rates were not significantly different across treatments, and all of them were higher than 97%. The protein and lipid content of Nile tilapia bodies and bioflocs decreased with increasing salinity, while the ash content increased. The highest body ash content in Nile tilapia (13.81% of dry weight) and bioflocs (31.78% dry weight) was found at 8 g/L salinity. Based on the present study, it is suggested that salinities of 4 and 8 g/L can improve water quality, growth performance, survival, and carcass composition of Nile tilapia fingerlings in the biofloc system. This finding suggests that brackish waters can be utilized for sustainable aquaculture for the rearing of Nile tilapia. [ABSTRACT FROM AUTHOR]

Some aspects of traditional aquaculture have negative impacts on the aquatic environment, leading to pollution and disease outbreaks in farmed organisms. Biofloc technology (BFT) is a closed aquaculture system that utilizes specific microbial communities to remove ammonia emitted from aquaculture organisms or adds carbon to the aquaculture system to improve water quality. BFT has benefits, such as increasing production and improving water quality, and reducing disease spread and pollution, without the need for water exchange. However, there are disadvantages, such as rapid changes in water quality due to accumulation of dissolved nutrients and total suspended soils (TSS) and the requirement for expensive aeration equipment to maintain dissolved oxygen. BFT can be enhanced in value and efficiency by combining it with other aquaculture technologies, such as aquaponics and vertical aquaculture to overcome the disadvantages. The integration of biofloc with technologies from the fourth industrial revolution holds potential for further development, while aquaponics and vertical farming can eliminate geographical limitations and accelerate the urbanization of aquaculture. The integration of aquaponics and vertical aquaculture with BFT has potential for development, accelerating the urbanization of aquaculture and removing geographic limitations. [ABSTRACT FROM AUTHOR]

Background: Shrimp cultured in a biofloc system (BFS) have a lower disease incidence than those farmed in a water exchange system (WES). Although a number of studies have reported that the gut bacterial community induced by BFS is highly associated with shrimp disease resistance, the causal relationship remains unknown. Here, the promotive roles of gut bacterial community induced by BFS in pathogenic Vibrio infection resistance and its potential micro-ecological and physiological mechanisms were investigated by gut bacterial consortium transplantation and synthetic community (SynCom) construction. Results: The BFS induced a more stable and resistant gut bacterial community, and significantly enriched some beneficial bacterial taxa, such as Paracoccus, Ruegeria, Microbacterium, Demequina, and Tenacibaculum. Transplantation of a gut bacterial consortium from BFS shrimp (EnrichBFS) greatly enhanced the stability of the bacterial community and resistance against pathogenic V. parahaemolyticus infection in WES shrimp, while transplantation of a gut bacterial consortium from WES shrimp significantly disrupted the bacterial community and increased pathogen susceptibility in both WES and BFS shrimp. The addition of EnrichBFS in shrimp postlarvae also improved the pathogen resistance through increasing the relative abundances of beneficial bacterial taxa and stability of bacterial community. The corresponding strains of five beneficial bacterial taxa enriched in BFS shrimp were isolated to construct a SynComBFS. The addition of SynComBFS could not only suppress disease development, but also improve shrimp growth, boost the digestive and immune activities, and restore health in diseased shrimp. Furthermore, the strains of SynComBFS well colonized shrimp gut to maintain a high stability of bacterial community. Conclusions: Our study reveals an important role for native microbiota in protecting shrimp from bacterial pathogens and provides a micro-ecological regulation strategy towards the development of probiotics to ameliorate aquatic animal diseases. 1NpdyYjfCEzGqNeY6CWHQH Video Abstract [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the water quality, growth performance, body composition, length–weight relationship, condition factors and benefit–cost analysis of giant freshwater prawn (Macrobrachium rosenbergii) cultured with biofloc system in pond conditions. The experiment was conducted in twelve (12) experimental ponds, each measuring 240 m2. The control group was cultured without any biofloc (T1), and biofloc‐based three treatments were biofloc with 100% feed (T2), biofloc with 90% feed (T3) and biofloc with 80% feed (T4). The biofloc‐based treatments showed significantly higher floc volume, total suspended solids, total heterotrophic bacteria and plankton density than the control (p < 0.05). All the growth parameters were significantly higher in biofloc‐based treatments (T2, T3 and T4) than in the control (T1). The lowest feed conversion ratio was found lowest in T4 (1.40 ± 0.02) and highest in T1 (2.13 ± 0.04), which was significantly different among the treatments (p < 0.05). The significantly highest production was obtained 939.02 ± 6.61 kg/ha in T2, and the lowest was 779.67 ± 7.50 kg/ha in T1. The length–weight relationship indicated positive allometric growth in all treatments. The condition factor ranged from 0.95 to 1.07, showing that the prawns were in good health throughout all treatments. The results of the present study indicated that M. rosenbergii can adapt to a biofloc‐based aquaculture system, and the conventional feeding rations can be reduced up to 20% without affecting the growth and production. [ABSTRACT FROM AUTHOR]

Osphronemus gourami, a promising Indonesian fish, requires optimal nutritional feed and water quality in a culture system to ensure successful commercialization. However, there is a lack of research on the effect of combining Chlorella vulgaris supplementation with biofloc and non-biofloc culture systems on amylase activity and blood urea levels in gourami fish. This study aims to investigate the impact of Chlorella vulgaris supplementation with different culture systems on the amylase activity of various digestive organs and blood urea levels in Osphronemus gourami. The experiment was conducted using a Factorial Completely Randomized Design with two factors. Gourami fish were fed with C. vulgaris at levels of 0, 2, 3, 4, and 5 g.kg-1 for a period of 28 days, and they were divided into biofloc and non-biofloc groups for the culture systems. Amylase activity was measured using three pH buffers, and blood urea levels were analyzed using a urea kit. The results of the study demonstrated that amylase activity significantly increased when supplemented with C. vulgaris at a level of 5 g.kg-1 feed using the biofloc system, leading to a decrease in blood urea levels. These findings suggest that C. vulgaris supplementation, combined with the biofloc system, can be an effective improvement. In conclusion, this research provides valuable insights into the use of Chlorella vulgaris supplementation and the biofloc system as alternative strategies for enhancing the amylase activity of various digestive organs and reducing blood urea levels in O. gourami, thereby improving their overall nutrition and water quality. [ABSTRACT FROM AUTHOR]

The purpose of this experiment was to study the effects of different cultural patterns on the growth performance,serum activity indicator,and immune responses of Litopenaeus vannamei. Two pilot-scale culture models of Litopenaeus vannamei,recirculating aquaculture system (RAS) and biofloc technology system (BS), were constructed in a greenhouse,each of which was 3 parallel. 100 000 larvae of Litopenaeus vannamei were placed in parallel,and the initial culture density was 500 ind/ m3. The water quality indicator of culture water was measured every other day,and after 100 days of feeding,the growth indicator,serum antioxidant activity indicator,and immune responses of Litopenaeus vannamei were measured. The results showed that there was no significant difference in ammonia nitrogen,nitrite,nitrate,temperature,pH value,and dissolved oxygen between RAS and BS groups,but nitrite accumulation in the BS group was nearly 20 days,which affected the growth of Litopenaeus vannamei. The specific growth rate, survival rate, and final density of the BS group were significantly lower than those of the RAS group (P <0. 05),but there was no significant difference in feed conversion factor (FCR) and condition factor (CF). There was no significant difference in the intestinal flora of shrimp in the two culture modes at the phylum level and significant difference at the genus level (P < 0. 05),with the highest abundance of norank_f_JG30_KF_CM45 in the RAS culture mode and the highest abundance of the genus Amaricoccus in the BS culture mode. In conclusion,RAS cultivation can achieve stable and controllable water quality indexes and then improve the growth performance of shrimp,but the production cost is slightly higher than BS cultivation. [ABSTRACT FROM AUTHOR]

FLOCponics is an integrated agri-aquaculture system, in which water and nutrients from a biofloc-based fish culture are reused to fertilise soilless plants. This paper is the first modelling study that focuses on decoupled FLOCponics with the aim of investigating and discussing whether the integration of biofloc-based culture with soilless plant production increases the efficiency of food production in terms of resource use and by how much. For this purpose, a biofloc-based monoculture system with a total volume of the fish tanks of 15.2 m3, and a FLOCponics system with similar biofloc system and a planting area of 33.6 m2 was modelled. The simulation models of these reference systems were run for a period of five years, and water, nitrogen and total suspended solid balances in both systems were compared. In addition to this, various planting areas of the FLOCponics system were changed step-wise until the most suitable size was found. The results indicate that FLOCponics is 10% and 27% more efficient in using water and nitrogen, respectively, than the stand-alone biofloc system. Also, the integrated system results in a reduction of 10% in the amount of solids discharged. Optimisation of the planting area with respect to key model outputs led to an improved FLOCponics system, where the planting area of the system is expanded by a factor of 3.2. The findings presented in this study support the hypothesis that integrating a biofloc system with hydroponics makes biofloc-based fish culture more efficient in terms of resource use and wastes avoidance. • The resource use efficiency of a biofloc and a FLOCponics system is compared. • The FLOCponics system is more efficient in using water than the biofloc system. • Nitrogen use efficiency is higher in the FLOCponics than in the biofloc system. • The FLOCponics system discharges 10% less solid waste than the biofloc system. • FLOCponics can possibly be made more efficient by expanding the planting area. [ABSTRACT FROM AUTHOR]

The present study was carried out to investigate the optimum stocking density for gonadal development, pigmentation, and survival of Carassius carassius stocked at varying stocking densities under a biofloc-based system. C. carassius (25 ± 0.15 g) were randomly distributed in sixteen tanks, each with 250 L water at the stocking densities viz. 1 kg/m3, 2 kg/m3, 3 kg/m3, 4 kg/m3 (10, 20, 30 and 40 fish/250 L). The carbon‑nitrogen ratio of 15:1 was maintained using wheat flour as a carbon source. The best gonad performance in terms of absolute fecundity (4449.98 ± 115.636), relative fecundity (114.67 ± 2.770), GSI (5.62 ± 0.018 and 2.93 ± 0.014 for females & males respectively), and advanced maturation stages (vitellogenic oocytes and seminiferous tubules with spermatozoa) was observed in the density treatment having 20 fish/250 L. The skin carotenoid content showed an increasing trend with maximum content (8.11 ± 0.018 μg/g)) recorded for the fish stocked at 20/250 L. The scales of the fish from the same treatment presented a higher concentration of yellow orange pigments giving an overall golden hue to the scales while as the density and dispersion of melanophores increased with an increase in stocking density giving an overall darker coloration to the fish, indicating a stressful condition at higher stocking density. The survival rate of fish showed no significant difference (p ≥0.05) between the various density groups. The results of this experiment elucidate that Carassius carassius could be cultured with better gonad performance, increased carotenoid content, and high survival at a stocking density of 2 kg/m3 in a biofloc system. [Display omitted] • Floc volume significantly affects the reproductive performance and pigmentation. • At higher fish density in Biofloc system, advanced stages of gonadal maturity are seen. • Carotenoid content in fish skin improves at higher stocking density, employing BFT. • In biofloc system, stocking density is an impact factor beyond a certain limit. • Higher dispersion of scale melanophores is seen as stocking density exceeds a limit. [ABSTRACT FROM AUTHOR]

The current study examined the combined effects of feeding rates and feeding types on the water quality, growth performance, digestive enzymes, blood parameters, and liver antioxidant enzymes of Nile tilapia (Oreochromis niloticus) fingerlings reared under a biofloc system. A 3 × 2 factorial experimental design was used with three feeding rates (2%, 3%, and 4%) and two feeding types (sinking or floating feed), comprising six treatments with three replicates. Fingerlings with an initial body weight of 4.50 ± 0.25 g were stocked in eighteen circular plastic tanks (0.5 m3) at a stocking density of 35 fish per tank fed three times a day at 10:00, 12:00 and 15:00. Starch was added to all treatments as an organic carbon source at a C/N ratio of 10:1. The phytoplankton community was determined to consist of twenty-two species, including individuals from the classes Cyanobacteria, Chlorophyceae, and Bacillariophyta. The most common phytoplankton classes were Chlorophyceae, followed by Cyanobacteria, and fish-fed floating feed at a feeding rate of 2% of total biomass yielded the greatest number of phytoplankton communities. Eight zooplankton species belonging to rotifers and protozoa were identified during this experiment. The highest values of final body weight, weight gain, and specific growth rate were recorded for a fish-fed floating diet with the highest feeding rate (4% of biomass). The highest hepatosomatic index (HIS) was detected in a fish-fed floating diet at a rate of 4% of total biomass. Though fish-fed sinking feed with a 4% biomass feeding rate presented the highest spleen index (SI). The highest significant (P 0.05) on hemoglobin (Hb), hematocrit (Hct), and red blood cells (RBCs). Feeding rate, feed type, and their interactions had no significant impact (P > 0.05) on serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), or albumin, but feeding rates or feed types had an effect (P

This study aimed to investigate the effects of mango peel powder (MGPP) on growth, innate immunity, and immune-antioxidant related gene expression of Nile tilapia reared under biofloc system. Three hundred Nile tilapia (average weight 14.78 ± 0.05 g) were distributed into 15 fiber tanks (300 L per tank) assigned to five treatments in triplication. Fish were fed basal diet containing different levels MGPP as follows: 0 (MGPP0: control), 6.25 (MGPP 6.25), 12.5 (MGPP 12.25), 25 (MGPP 25), and 50 (MGPP 50) g kg−1 diet for 8 weeks. Specific growth rate (SGR), weight gain (WG), final weight (FW), feed conversion ratio (FCR), skin mucus of lysozyme (SMLA), and peroxidase activities (SMPA), serum of lysozyme (SL) and peroxidase (SP) were measured every for weeks; while immune-antioxidant-related gene expressions were determined after 8 weeks post-feeding. The results indicated that MGPP 25 diet resulted in higher SGR, WG, FW, and FCR but no significant differences among treatments were noticed. In terms of immune responses, lysozyme and peroxidase activities in mucus and serum were significantly higher in MGPP 12.5 and MGPP 25 diets against the control. Similarly, significant up-regulation of IL-1 and IL-8 gene expressions was observed in fish fed MGPP 25 against the control. However, no significant differences in LBP , GSTa , GPX , and GSR among treatments were observed. Overall, dietary inclusion of MGPP 25 significantly enhanced immune response and immune related gene expressions but not growth performance and antioxidant gene expressions. The results implied that MGPP can be potentially used as an immunostimulants in Nile tilapia culture. • MGPP supplemented diet did not affect growth and feed utilization of Nile tilapia. • Significantly improved skin mucus and serum immunities was noted in fish fed MGPP 25. • Significant up-regulation IL-1 and IL-8 gene expressions were observed in fish fed MGPP 25. • No significant differences in LBP, GSTa, GPX, and GSR among treatments were observed. [ABSTRACT FROM AUTHOR]

Biofloc technology is commonly applied in intensive tilapia (Oreochromis niloticus) culture to maintain water quality, supply the fish with extra protein, and improve fish growth. However, the effect of dietary supplementation of processed biofloc on the gut prokaryotic (bacteria and archaea) community composition of tilapia is not well understood. In this study one recirculating aquaculture system was used to test how biofloc, including in-situ biofloc, dietary supplementation of ex-situ live or dead biofloc, influence fish gut prokaryotic community composition and growth performance in comparison to a biofloc-free control treatment. A core gut prokaryotic community was identified among all treatments by analyzing the temporal variations in gut prokaryotes. In-situ produced biofloc significantly increased the prokaryotic diversity in the gut by reducing the relative abundance of dominant Cetobacterium and increasing the relative abundance of potentially beneficial bacteria. The in-situ biofloc delivered a unique prokaryotic community in fish gut, while dietary supplementation of tilapias with 5% and 10% processed biofloc (live or dead) only changed the relative abundance of minor prokaryotic taxa outside the gut core microbiota. The modulatory effect of in-situ biofloc on tilapia gut microbiota was associated with the distinct microbial community in the biofloc water and undisturbed biofloc. The growth-promoting effect on tilapia was only detected in the in-situ biofloc treatment, while dietary supplementation of processed biofloc had no effect on fish growth performance as compared to the control treatment. [ABSTRACT FROM AUTHOR]

The present study evaluated the effects of different carbohydrates materials used as carbon sources on water quality, biofloc quality, and growth and productive performance of Nile tilapia (Oreochromis niloticus) reared in biofloc (BFT)-based cement ponds (25 m x 10 m x 1.2 m; with 250 m3 volume). Nile tilapia fingerlings (44.9±1.9 g) were distributed into nine ponds at a density of 40 fish per 1 m3 (10000 fish/pond) to represent three treatments in triplicates. The control ponds received no carbon source addition; meanwhile sugarcane molasses (MO) and wheat flour (WF) were added to ponds. A commercial diet (30% crude protein) was offered to fish in each pond at levels of 3% and 2% of live body weight of fish in the control and BFT-based ponds, respectively, for 12 weeks. The amounts of feed were divided equally to three equal portions and offered to fish at 9:00, 13:00, and 17:00 h. The control ponds' water was replaced by 50% every day with new water; meanwhile in MO and WF ponds, water loss via evaporation or leakage was compensated to reach the 1.0 m depth only. The pH value as well as unionized ammonia and nitrite levels, in the present study, were significantly lower, meanwhile nitrate and total suspended solids levels were significantly higher in MO and WF-treated ponds than the control one. The WF treatment resulted in significantly larger biofloc volume and higher total bacterial count compared to the MO treatment. The highest growth and production indices of Nile tilapia were observed in the BFT-based treatments as compared with the control group; particularly at the WF treatment followed by the MO treatment. In conclusion, the WF addition to cement fishponds is a more beneficial carbonaceous source for the efficient water quality, biofloc biomass, and growth and productivity of Nile tilapia reared in BFT-based system. [ABSTRACT FROM AUTHOR]

Abstract Background Fish gut microbial colonisation starts during larval stage and plays an important role in host’s growth and health. To what extent first colonisation could influence the gut microbiome succession and growth in later life remains unknown. In this study, Nile tilapia embryos were incubated in two different environments, a flow-through system (FTS) and a biofloc system (BFS); hatched larvae were subsequently cultured in the systems for 14 days of feeding (dof). Fish were then transferred to one common recirculating aquaculture system (RAS1, common garden, 15–62 dof), followed by a growth trial in another RAS (RAS2, growth trial, 63–105 dof). In RAS2, fish were fed with two types of diet, differing in non-starch polysaccharide content. Our aim was to test the effect of rearing environment on the gut microbiome development, nutrient digestibility and growth performance of Nile tilapia during post-larvae stages. Results Larvae cultured in the BFS showed better growth and different gut microbiome, compared to FTS. After the common garden, the gut microbiome still showed differences in species composition, while body weight was similar. Long-term effects of early life rearing history on fish gut microbiome composition, nutrient digestibility, nitrogen and energy balances were not observed. Still, BFS-reared fish had more gut microbial interactions than FTS-reared fish. A temporal effect was observed in gut microbiome succession during fish development, although a distinct number of core microbiome remained present throughout the experimental period. Conclusion Our results indicated that the legacy effect of first microbial colonisation of the fish gut gradually disappeared during host development, with no differences in gut microbiome composition and growth performance observed in later life after culture in a common environment. However, early life exposure of larvae to biofloc consistently increased the microbial interactions in the gut of juvenile Nile tilapia and might possibly benefit gut health.

This study aimed to investigate the adaptability of commercial probiotics to the biofloc system, as well as the influence on bacterial community, water quality and aquatic animal growth. Two biofloc systems nursing Litopenaeus vannamei postlarvae for 28 days were designed, the control (cBFT) and pBFT with addition of commercial probiotics (containing Bacillus , Clostridium , Enterococcus , Lactobacillus and Rhodopseudomonas). Results showed that at the end of the experiment, only the absolute abundance and the proportion of Bacillus contained in commercial probiotics (2.1 ± 0.8 × 105 genome copies mL−1 and 0.12 ± 0.03%) significantly increased in pBFT compared to those in cBFT (1.7 ± 0.8 × 104 genome copies mL−1 and 0.03 ± 0.02%), respectively (P < 0.05). Absolute abundances and proportions of several autochthonal bacterial genera (i.g., Acinetobacter , Anaerospora , Arthrobacter , Devosia , Luteolibacter , Marivita and Mycobacterium) also significantly elevated in pBFT (P < 0.05). Total suspended solids (TSS) and turbidity (415.2 ± 79.6 mg L−1 and 379.0 ± 86.4 NTU) were significantly higher in pBFT than both parameters in cBFT (118.1 ± 23.9 mg L−1 and 109.4 ± 44.3 NTU), respectively (P < 0.05). Whereas, zootechnical indices (except survival rate) were significantly lower in pBFT than those in cBFT, respectively (P < 0.05). The integrated impact model of commercial probiotics explained 57.9%–77.1% variations of shrimp growth performance, and showed that commercial probiotics as well as some autochthonal bacteria positively correlated with turbidity which in turn negatively correlated with zootechnical indices (P < 0.05). The findings suggested that added probiotics (especially Bacillus) induced changes on the autochthonal bacterial community, leading to changes of water quality which consequently resulted in the depression of growth performance of shrimp. [Display omitted] • Bacillus in the commercial probiotics mixture well adapted to biofloc system. • Commercial probiotics did not show benefit on shrimp growth unexpectedly. • Changes on autochthonal bacterial community alleviated probiotics' effects. • Probiotics alone contributed 8.0%–14.7% of variations on growth performance. • The integrated model explained 57.9%–77.1% of variations on shrimp growth. [ABSTRACT FROM AUTHOR]

The Saemangeum region of Jeollabuk province, located in the central region of the western coast of the South Korea, was once a representative fishing area in Korea. However, as the fishery environment has changed significantly due to the Saemangeum development project that started in 1991, the production of aquaculture has decreased by approximately 50% (from 164,141 tons in 1989 to 82,664 tons in 2019), fishermen's income has decreased, and the local economy has stagnated. The aquaculture industry in this area is limited in part because the Saemangeum Reservoir (35°52′07.3″N, 126°30′29.8″E) became unsuitable for the use as water for aquaculture; the aquaculture industry was not activated. In order to solve this problem, an alternative to using the Saemangeum Reservoir for aquaculture was needed. In order to determine the feasibility of using water from the reservoir, a low‐salinity artificial reservoir, as water for aquaculture of Litopenaeus vannamei, a biofloc technology (BFT) system was applied. The BFT system was applied to three experimental groups; the control group using seawater (CON), the experimental group using unfiltered water from the Saemangeum Reservoir (SW) and the experimental group using Saemangeum Reservoir filtered with micro‐membrane filtration technology (FW). Shrimps averaging 0.67 ± 0.01 g (Mean ± SD) were randomly distributed into nine acrylic 50 L tanks at a density of 20 shrimps per tank. The experiment was carried out for 6 weeks without a water change. At the end of the 6 weeks, there were no significant differences in the growth performance, feed efficiency, survival rate or biochemical parameters of L. vannamei among the groups. A water quality analysis indicated that the total ammonia nitrogen, NO2− and NO3− concentrations of all groups tended to rise similarly during the experimental period, and there was no significant difference between groups. In this study, it was found that when using BFT system, the water of the Saemangeum Reservoir can be used as culturing water for L. vannamei even if the influent water is not filtered with micro‐membrane filtration technology. Therefore, our study findings suggest that the water of the Saemangeum Reservoir, a low‐salinity artificial lake, can be used for inland aquaculture of L. vannamei when a BFT system is applied. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of biofloc on body composition, plasma protein, lipid profile, zooplankton community, and economics of Nile tilapia fingerlings in different stocking densities. Three stocking densities (200, 300 and 400 fish/m3) under biofloc system (BS) and clear system (CS) were applied. Nile tilapia with an initial body weight of 20.35 ± 0.35 grams were stocked in 18 cylindrical fiberglass tanks with a water volume of 50 liters for 75 days. Starch was added on Biofloc system treatments as a carbon source to set the C / N ratio at 15/1. Body proximate composition showed that the highest protein and ash content were recorded in the highest stocking density (400/m3). The highest fat content was noticed in the lowest density of 200/m3. For system conditions, the biofloc system showed significantly higher dry matter, fat, and ash content, compared to the clear water system. Biofloc sample analysis showed an increase in protein, fat, and ash contents with increasing stocking density. The highest stocking density of 400/m3 showed the highest significant (P<0.05) total protein, albumin, and globulin. Plasma total cholesterol, triglyceride, HDL, and LDL were all significantly higher in the lowest density (200/m3) than the other treatments. Biofloc system results recorded significantly higher total protein, albumin, globulin albumin/globulin ratio than the clear system. In addition, cholesterol triglyceride, and LDL were significantly increased with BFT treatments. All biofloc treatments showed higher zooplankton count, when compared with the clear system. Under biofloc conditions, increasing stocking density led to an elevation in zooplankton count as the highest was recorded for a density of 400 fish/m3. Three groups of organisms were identified, Rotifera, Protozoa, and Copepoda. Economical benefits in terms of feed costs and relative feed costs per kg of fish were recorded in the treatments of (BS) with superiority of stocking density of 200 fish/m3 under these experimental conditions. [ABSTRACT FROM AUTHOR]

The aim of the current study was to evaluate the growth of Arthrospira platensis in the effluent of Pacific white shrimp Litopenaues vannamei grown in biofloc systems. In the first experiment, A. platensis grew for 12 days in different dilutions (100, 10, 1%) of effluent and in the fertilizer medium in order to determine ideal dilution for the growth of the microalgae in the effluent. At the end of the experiment, the biofloc 100% treatment showed a significantly higher cell density than the fertilizer medium treatment. A second experiment, which lasted for 20 days, was conducted in order to evaluate the growth and bioremediation potential in treatments without total suspended solids, which were removed by decantation, and untreated effluent. The final biomass in the biofloc treatment was 0.50 ± 0.59 g/L and 0.18 ± 0.14 g/L in the biofloc decanted treatment. Both treatments removed 90% of phosphate from the effluent. Nitrate values oscillated throughout the experiment. Thus, it is possible to affirm that the cultivation of A. platensis can be used as a tool to reduce the nitrogen and phosphate loads in the effluent of L. vannamei raised in biofloc systems. [ABSTRACT FROM AUTHOR]

Although increasing attention has been attracted to the study and application of biofloc technology (BFT) in aquaculture, few details have been reported about the bacterial community of biofloc and its manipulation strategy for commercial shrimp production. An 8-week trial was conducted to investigate the effects of three input C/N ratios (8:1, 12:1 and 16:1) on the bacterial community of water biofloc and shrimp gut in a commercial BFT tank system with intensive aquaculture of P. vannamei. Each C/N ratio group had three randomly assigned replicate tanks (culture water volume of 30 m3), and each tank was stocked with juvenile shrimp at a density of 300 shrimp m−3. The tank systems were operated with zero-water exchange, pH maintenance and biofloc control. During the trial, the microbial biomass and bacterial density of water biofloc showed similar variation trends, with no significant difference under respective biofloc control measures for the three C/N ratio groups. Significant changes were found in the alpha diversity, composition and relative abundance of bacterial communities across the stages of the trial, and they showed differences in water biofloc and shrimp gut among the three C/N ratio groups. Meanwhile, high similarity could be found in the composition of the bacterial community between water biofloc and shrimp gut. Additionally, nitrogen dynamics in culture water showed some differences while shrimp performance showed no significant difference among the three C/N ratio groups. Together, these results confirm that the manipulation of input C/N ratio could affect the bacterial community of both water biofloc and shrimp gut in the environment of a commercial BFT system with intensive production of P. vannamei. Moreover, there should be different operations for the nitrogen dynamics and biofloc management during shrimp production process under different C/N ratios. [ABSTRACT FROM AUTHOR]

Growth, body composition and antioxidant status of Litopenaeus vannamei under zero water exchange biofloc-based culture system using inland saline groundwater (ISGW) were evaluated during the 60-day culture period in four varying stocking densities of 60 (T1), 100 (T2), 140 (T3) and 180 (T4) juvenile shrimps m-3. The carbon : nitrogen ratio was maintained at 15:1 using sugarcane molasses. Shrimp in the BFT treatments performed significantly better (P < 0.05) than control in terms of survival (98%-100%), weight gain (10.83 to 7.68g), feed conversion ratio (1.19 to 1.30) and feed efficiency ratio (0.88-0.84) at the end of the experimental period. Higher level of crude protein (29.1% to 33.0%), lipid (5.0% to 5.6%) and ash (1.4% to 1.6%) content was observed in the tissues of the shrimps from the BFT treatments when compared to control. Antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in gills, hepatopancreas and muscle were higher in the BFT treatments than in the control. These results indicate that microbial protein from recycled waste functions as nutrient, growth promoter and antioxidant capacity stimulator in shrimp reared in BFT using ISGW. [ABSTRACT FROM AUTHOR]

The biofloc system has recently attracted great attention as a cost-effective, sustainable, and environmentally friendly technology and expected to contribute toward human food security (Zero Hunger SDG 2). It is also expected that this endeavor can be adopted widely because of its characteristics of zero water exchange and reduced artificial feeding features. In the biofloc system, the flocs which are generally formed by aggregation of heterotrophic microorganisms, serve as natural bioremediation candidates. These microbes effectively maintain water quality by utilizing the nutrient wastes, mostly originated from digested, unconsumed, and metabolic processes of feed. Additionally, the flocs are important sources of nutrients, mainly a protein source, and when these are consumed by aquaculture animals they improve the growth performance, immunity, and disease tolerance of host against pathogenic microbial infection. Here in this review, we focus on recent advances that could provide a mechanistic insight on how the microbial community developed in the biofloc system helps in the bioremediation process and enhances the overall health of the host. We have also tried to address the possible role of these microbial communities against growth and virulence of pathogenic microbes.

The biofloc system has recently attracted great attention as a cost-effective, sustainable, and environmentally friendly technology and expected to contribute toward human food security (Zero Hunger SDG 2). It is also expected that this endeavor can be adopted widely because of its characteristics of zero water exchange and reduced artificial feeding features. In the biofloc system, the flocs which are generally formed by aggregation of heterotrophic microorganisms, serve as natural bioremediation candidates. These microbes effectively maintain water quality by utilizing the nutrient wastes, mostly originated from digested, unconsumed, and metabolic processes of feed. Additionally, the flocs are important sources of nutrients, mainly a protein source, and when these are consumed by aquaculture animals they improve the growth performance, immunity, and disease tolerance of host against pathogenic microbial infection. Here in this review, we focus on recent advances that could provide a mechanistic insight on how the microbial community developed in the biofloc system helps in the bioremediation process and enhances the overall health of the host. We have also tried to address the possible role of these microbial communities against growth and virulence of pathogenic microbes. [ABSTRACT FROM AUTHOR]

An eight-week investigation was conducted to access the potential impact of dietary watermelon rind powder (WMRP) and L. plantarum CR1T5 (LP) administered individually or in combination on immunity, disease resistance, and growth rate of Nile tilapia fingerlings cultured in a biofloc system. Three hundred twenty fish (average weight 16.57 ± 0.14 g) were distributed into 16 tanks at a rate of 20 fish per tank. The fish were fed different diets: Diet 1 (0 g kg−1 WMRP and 0 CFU g−1 L. plantarum) (control), Diet 2 (40 g kg−1 WMRP), Diet 3 (108 CFU g−1 LP), and Diet 4 (40 g kg−1 WMRP + 108 CFU g−1 LP) for eight weeks. A completely randomized design (CRD) with four replications was applied. Skin mucus, serum immunity, and growth parameters were analyzed every 4 weeks, and a challenge study against S. agalactiae was conducted at the end of the experiment. The findings showed that the inclusion of WMRP + LP, administrated individually or in a mixture, significantly (P<0.05) stimulated growth, skin mucus, and serum immune parameters of Nile tilapia fingerlings compared with the control. The highest values were detected in fish fed the combination of WMRP and LP, as opposed to individual administration of either WMRP or LP, in which no significant differences were detected. Within the challenge study, the relative percent survival (RPS) in Diet 2, Diet 3, and Diet 4 was 48.0%, 52.0%, and 68.0%, respectively. Fish fed 40 g kg−1 WMRP + LP produced significantly higher RPS and protection against S. agalactiae than the other treated groups. Current results suggest that the dual administration of WMRP and LP maybe an effective feed additive for Nile tilapia grown in an indoor biofloc system, capable of improving growth parameters and increasing resistance to S. agalactiae infection. • Combination of WMRP and L. plantarum significantly enhanced growth and feed utilization. • Significantly improved skin mucus and serum immunities was found in fish fed WMRP and L. plantarum. • WMRP and L. plantarum significantly increased survival rate of O. niloticus against S. agalactiae. [ABSTRACT FROM AUTHOR]

Biofloc technology (BFT) is widely applied in aquaculture. The present study was carried out to evaluate the effects of different carbon sources on microbial population in BFT system. Four carbon sources, glucose (Glu), molasses (Mol), polybutylene succinate (PBS) and polyhydroxy butyrate‐hydroxy valerate (PHBV), were tested in a 44‐day trial. No carbon sources were added in control (Con). Results showed that DO, total alkalinity and biofloc volume were significantly different among treatments. Total ammonia nitrogen (TAN) accumulation was observed during the first 14 days, and the nitrite nitrogen and nitrate nitrogen increased from day 9 to 19 in all treatments. Proteobacteria and Bacteroidetes were the most abundant phyla in all the treatments. The unweighted pair‐group method with arithmetic means tree and principal coordinate analysis (PCoA) indicated that the distribution of microbial community was categorized into three groups. Glu and Mol formed two separate groups, the other treatments formed the third category. Chemoheterotrophy and aerobic chemoheterotrophy were the two most abundant functions, and the percentage of the occurrence of these two functions in Con was 70.5%, highest among treatments. PCA and function annotation indicated that the Glu and Con had different functional compositions compared with the other groups. The Glu had a more diverse functional composition. Overall, the glucose can be best used by the microorganisms. With low biofloc volume, the selection of PBS and PHBV as carbon sources in BFT needs to be further studied to achieve maximum effectiveness. [ABSTRACT FROM AUTHOR]

Feed frequency is one of the factors that have great effect on feed utilization. This factor was previously examined under clear water condition but not under biofloc condition. Different feed frequencies (FF); one (FF1), two (FF2), three (FF3), four (FF4) and five (FF5) times a day were evaluated under biofloc system condition. Fish with initial body weight of 7.9 g ± 0.03 were stocked (20 fish tank−1) in fifteen tanks (55 L). Total ammonia, nitrite, nitrate, and pH values were within acceptable limits for Nile tilapia. No significant differences were recorded among different feeding frequency treatments regarding growth performance parameters. FF2 and FF5 groups had the best significant values for feed conversion and protein efficiency ratios. Ash content of the collected biofloc slightly differed(P ≤ 0.05) among treatments. The highest zooplankton count was recorded for FF5 treatment while, the lowest was recorded for FF2 treatment. Rotifers was the most dominant group (70–92 %) and the highest percentage were recorded for FF2 (92.4 %). FF5 showed a unique development in zooplankton community where, nematodes only appeared in this treatment. From economical prospective, feeding tilapia juveniles twice daily under biofloc condition will save labor costs or feeder energy and improve feed utilization than other frequencies.

The biofloc system is a relatively new aquaculture technology that offers practical solution to maintain culture water quality by recycling nutrients and improves the health status and resistance of shrimps against microbial infection, yet the mode of action involved remains unclear. This study aimed to unravel the underlying mechanism behind the protective effect of a biofloc system using Litopenaeus vannamei and acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio parahaemolyticus M0904 strain as a host-pathogen model. The results showed that a biofloc system maintained at a C/N ratio of 15, improves the water quality and contributes to the nutrition of cultured animals as bioflocs might serve as an additional protein source. Furthermore, the study demonstrated that the biofloc system enhances the survival of L. vannamei upon challenge with a V. parahaemolyticus AHPND strain. Remarkably, the results highlight that in the biofloc system, AHPND-causing V. parahaemolyticus possibly switch from free-living virulent planktonic phenotype to a non-virulent biofilm phenotype, as demonstrated by a decreased transcription of flagella-related motility genes (flaA, CheR, and fliS), Pir toxin (PirBVP), and AHPND plasmid genes (ORF14) and increased expression of the phenotype switching marker AlkPhoX gene in both in vitro and in vivo conditions. Taken together, results suggest that biofloc steer phenotype switching, contributing to the decreased virulence of V. parahaemolyticus AHPND strain toward shrimp postlarvae. This information reinforces our understanding about AHPND in a biofloc setting and opens the possibility to combat AHPND not only by trying to eliminate the AHPND-causing V. parahaemolyticus from the system but rather to steer the phenotypic switch.

Although increasing attention has been attracted to the study and application of biofloc technology (BFT) in aquaculture, few details have been reported about the bacterial community of biofloc and its manipulation strategy for commercial shrimp production. An 8-week trial was conducted to investigate the effects of three input C/N ratios (8:1, 12:1 and 16:1) on the bacterial community of water biofloc and shrimp gut in a commercial BFT tank system with intensive aquaculture of P. vannamei. Each C/N ratio group had three randomly assigned replicate tanks (culture water volume of 30 m3), and each tank was stocked with juvenile shrimp at a density of 300 shrimp m−3. The tank systems were operated with zero-water exchange, pH maintenance and biofloc control. During the trial, the microbial biomass and bacterial density of water biofloc showed similar variation trends, with no significant difference under respective biofloc control measures for the three C/N ratio groups. Significant changes were found in the alpha diversity, composition and relative abundance of bacterial communities across the stages of the trial, and they showed differences in water biofloc and shrimp gut among the three C/N ratio groups. Meanwhile, high similarity could be found in the composition of the bacterial community between water biofloc and shrimp gut. Additionally, nitrogen dynamics in culture water showed some differences while shrimp performance showed no significant difference among the three C/N ratio groups. Together, these results confirm that the manipulation of input C/N ratio could affect the bacterial community of both water biofloc and shrimp gut in the environment of a commercial BFT system with intensive production of P. vannamei. Moreover, there should be different operations for the nitrogen dynamics and biofloc management during shrimp production process under different C/N ratios.

In spite of various advantages of biofloc technology in aquaculture, few studies have focused on the health status of fish in biofloc system. In this survey, the effect of cane molasses as a carbon source of biofloc system on hemato-immunological parameters, antioxidant status, and stress indicators of common carp (Cyprinus carpio) was investigated. Four hundred and twenty juvenile common carp (40.2 ± 5.76 g) were randomly divided into four equal groups in triplicates as follows: groups A, B, and C were reared in biofloc system with molasses as a carbon source with C/N ratio of 15, 20, and 25, respectively, whereas control group (D) was reared in similar intensity without biofloc system. Fish were reared for 90 days and samples were taken on days 0, 30, 60, and 90 of the experiment. Immunological parameters including serum lysozyme and bactericidal activity, serum complement and IgM level, and NBT reduction and resistance to bacterial challenge as well as hematological parameters (RBC, WBC, hematocrit, hemoglobin) were assessed in experimental groups. Meanwhile, antioxidative enzyme activity (glutathione and superoxide dismutase, catalase) and stress indicators (glucose and cortisol level) were measured and compared among the groups. Water quality parameters were evaluated in all groups. Results showed that most of the immunological parameters as well as resistance against bacterial infection increased in biofloc groups (particularly in C/N = 20 groups) (P < 0.05). Hematological parameters and antioxidative enzyme activity were not affected by biofloc systems. Stress indicators showed a significant decrease in biofloc system, particularly in C/N = 20 group compared with control (P < 0.05). The results indicated that biofloc system (particularly C/N ratio = 20 groups) could not only improve immunological parameters, antioxidative status, and water quality but it decreased stress statues of common carp. [ABSTRACT FROM AUTHOR]

A feeding trial was carried out to examine the effects of adding chestnut (Castanea sativa) polyphenols (CSP) on the growth, skin mucus and serum immune parameters of Nile tilapia (Oreochromis niloticus). Five experimental diets with inclusion levels of 0, 1, 2, 4, and 8 g kg−1 of CSP were fed to Nile tilapia fingerlings (12.77 ± 0.17 g fish−1) during an eight-week trial. Fish were analyzed on the fourth and eighth week to determine the influences of CSP on growth, skin mucus, and serum immune parameters. Challenging test versus Streptococcus agalactiae was evaluated at the end of the trial. Fish fed with CSP enriched diets displayed a significant increase (P ≤ 0.05) in growth and a decline in feed conversion ratio (P ≤ 0.05). Similarly, skin mucus and serum immune parameters were significantly increased (P ≤ 0.05) in fish fed CSP with respect to the control. The effects were already evident four weeks after the CSP administration. The disease protection test displayed that the fish's survival rate was significantly higher (P < 0.05) in CSP diets over the control. The relative percentage of survival (RSP) was 62.5, 75.0, 58.3, and 37.5 in fish fed diets contained 1, 2, 4, and 8 g kg−1 CSP, respectively. The best effect on growth, immune response, and disease resistance were shown in Nile tilapia fed with a diet supplementation of 2 g kg−1 CSP. • Supplementation of 2 g kg−1 CSP significantly enhanced growth parameters and FCR of O. niloticus. • Significant increases skin mucus and serum immunities were observed in fish fed 2 g kg−1 CSP. • Significant declines mortality was found in fish fed 2 g kg−1 CSP against Streptococcus agalactiae. [ABSTRACT FROM AUTHOR]

Functional foods have molecules that promote health benefits beyond their nutritional qualities. In this context, the zootechnical performance, color, and biochemical responses of Pacific white shrimp (Litopenaeus vannamei) fed with different levels of açaí (Euterpe oleracea), a fruit with unique antioxidant characteristics, were observed. Four diets with different levels of inclusion of lyophilized açaí (0.0%, 2.5%, 5.0%, and 10.0% W/W) were administered to shrimps reared in biofloc technology (BFT) systems. After 43 days, the zootechnical parameters (weight gain, feed conversion ratio, and specific growth rate) and coloration in fresh and cooked shrimps were measured, and the L*, a*, and b* parameters were estimated with a digital colorimeter. Survival and growth performances were not affected by açaí inclusion in diets. Açaí inclusion modulates the flavonoid content in the gills of L. vannamei and in the bioflocs of the rearing BFT system. As in the diet of 10.0% açaí, performed with a total replacement of fish oil without affecting growth, we propose the use of açaí as a vegetal oil source for shrimp feeding in BFT systems. Açaí also induced the reddish color in fresh and cooked L. vannamei, an influential factor in their commercial value. [ABSTRACT FROM AUTHOR]

This document is an updated review on the use of probiotics to the freshwater prawn Macrobrachium sp. culture in biofloc systems, pointing out the benefits in growth, survival, improvements in the immune system, pathogen control, and water quality. The review also emphasizes some aspects that need to be defined with greater accuracy, like the effect of doses and times of probiotic administration and refers to bacterial dynamics associated with biofloc. This review aims to enhance the knowledge of probiotics in commercially important species such as the freshwater prawn. [ABSTRACT FROM AUTHOR]

The biofloc system is a relatively new aquaculture technology that offers practical solution to maintain culture water quality by recycling nutrients and improves the health status and resistance of shrimps against microbial infection, yet the mode of action involved remains unclear. This study aimed to unravel the underlying mechanism behind the protective effect of a biofloc system using Litopenaeus vannamei and acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio parahaemolyticus M0904 strain as a host-pathogen model. The results showed that a biofloc system maintained at a C/N ratio of 15, improves the water quality and contributes to the nutrition of cultured animals as bioflocs might serve as an additional protein source. Furthermore, the study demonstrated that the biofloc system enhances the survival of L. vannamei upon challenge with a V. parahaemolyticus AHPND strain. Remarkably, the results highlight that in the biofloc system, AHPND-causing V. parahaemolyticus possibly switch from free-living virulent planktonic phenotype to a non-virulent biofilm phenotype, as demonstrated by a decreased transcription of flagella-related motility genes (flaA , CheR , and fliS), Pir toxin (PirB VP ), and AHPND plasmid genes (ORF14) and increased expression of the phenotype switching marker AlkPhoX gene in both in vitro and in vivo conditions. Taken together, results suggest that biofloc steer phenotype switching, contributing to the decreased virulence of V. parahaemolyticus AHPND strain toward shrimp postlarvae. This information reinforces our understanding about AHPND in a biofloc setting and opens the possibility to combat AHPND not only by trying to eliminate the AHPND-causing V. parahaemolyticus from the system but rather to steer the phenotypic switch. [ABSTRACT FROM AUTHOR]

Litopenaeus setiferus has been described as an economically important native species ranging from the north Atlantic along the coast of the Gulf of Mexico to Florida. Its reproduction has been studied in captivity, as well as some aspects of its nutritional physiology, diseases and adaptation to various environments, including nurseries. In terms of growth, L. setiferus has been compared with L. vannamei for its performance in ponds. As a native species, L. setiferus benefits local fisheries and is also used as a bait shrimp for recreational activity. The present review covers background information and recent advances in research and development efforts to determine its potential both for aquaculture in ponds and intensive biofloc systems (BFT), as well as for the stocking of fishing grounds. The collective research advances for this species presented in this review could help to sustain various strategies, including highly intensive techniques, to rehabilitate L. setiferus in connection with potential institutes. [ABSTRACT FROM AUTHOR]

Intensification of aquaculture could be achieved by overcoming major constraints like the development of a sustainable system to protect the environment, development of a reasonable cost/benefit ratio and using significantly less natural resources like water and land. Biofloc technology is state of the art and is gaining in popularity due to its many potential benefits. It is underlined by restricting water exchange through the use of waste due to environmental regulations and provides a biosafety system that minimizes disease compared to other existing culture systems. Biofloc also helps to reduce feed costs, which account for 60% of the operating costs in the aquaculture system, by lowering the feed rate, as the microbial flocs protein can act as additional feed. [ABSTRACT FROM AUTHOR]

An experiment for a period of 60 days was performed with species specific mineral supplementation in biofloc system for GIFT tilapia reared in inland saline water. Four different concentrations of formulated mineral mixture (10, 15, 20, 25 g L−1) were supplemented in the subculture of biofloc inoculum for different treatments (T1, T2, T3, and T4). In contrast, two control groups (conventional culture system (C) and a standard biofloc control (BC) devoid of mineral supplements) were maintained. Major water quality parameters were optimal except alkalinity and pH, which were fluctuated in the treatment groups, and higher turbidity was noticed only in the T4 group. The minerals supplemented groups had lower levels of TAN, nitrite (NO 2) and nitrate (NO 3) than conventional biofloc system (BC). Floc parameters such as floc volume, total suspended solids (TSS), total dissolved solids (TDS) and total solids (TS) were higher than the control. Haematological parameters Hb (haemoglobin) and WBC (white blood corpuscles) of fish reared in treatments were higher, ranging from (8.2 ± 0.64 −10.47 ± 0.66 g dL−1) and (187.83–215.17 ± 6.58 per cumm) respectively (P < 0.05) compared to both the controls. Serum parameters of fish was recorded to be higher in T2. The proximate composition analysis revealed an enhanced crude protein content (33.22 ± 1.00%, 67.68 ± 0.2%) and crude lipid (5.24 ± 0.22% & 15.18 ± 0.58%) (P > 0.05) content from BC, but ash content (39.11 ± 0.1% & 20.35 ± 0.21%) from T4 in both dried biofloc and fish samples were higher than rest of the groups. Specific growth rate (SGR) and weight gain (WG) were recorded to be significantly higher in the T2 group. Feed conversion ratio (FCR) was observed to be better in all the treatments and the BC group than conventional control. The current investigation showed that subculture of biofloc inoculum supplemented with formulated mineral mix of 15 g L−1 could be effective in terms of water quality maintenance, feed utilization, growth, survival and biochemical parameters of GIFT tilapia reared in inland saline ground water. [ABSTRACT FROM AUTHOR]