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This study was conducted to investigate the combined effects of probiotic yeast, Saccharomyces cerevisiae, and lactic acid bacteria, Lactobacillus casei on the growth performance, biochemical response, cytokine gene expression, gut histomorphology and microbial composition of juvenile barramundi, Lates calcarifer. Barramundi juveniles with an initial mean weight of 12.17 ± 0.15 g were randomly allocated into 8 tanks (300L) at a density of 20 fish per tank and fed either a basal diet (control), or the same basal diet supplemented with 1% of S. cerevisiae and 1% of L. casei, collectively termed ‘probiotic’, for 56 days in quadruplicate. Results indicate that dietary probiotic supplementation produced significant (P

Poultry by-product meal (PBM) as a replacement for fish meal (FM), an expensive and unsustainable protein aquafeed ingredient, has been tested on different aquaculture fish species. However, the complete replacement of FM with a mixture of PBM and Hermetia illucens (HI) larvae in barramundi culture has not been previously investigated. In this study, results are presented on growth performance, fillet fatty acid composition, serum metabolites, skin mucosal barriers, hepatic steatosis, antioxidant activity, and immunity of juvenile barramundi, Lates calcarifer fed either a FM-based diet (0PBM-0HI) or two test diets in which total FM protein was replaced by a mixture of 70% PBM and 30% full-fat (FHI) and defatted HI larvae (DHI) meal (designated as 70PBM-30FHI and 70PBM-30DHI). After 56 days of feeding, the results showed that the growth was affected when fish were fed 70PBM-30DHI with a higher feed conversion ratio (FCR) with respect to 0PBM-0HI and 70PBM-30FHI diets. There was no variation in growth performance, feed utilization, and FCR between 0PBM-0HI and 70PBM-30FHI. The retention of total saturated and monounsaturated fatty acids increased in the fillet of juveniles fed 70PBM-30FHI and 70PBM-30DHI while total retention of polyunsaturated (PUFA), n-3 PUFA, and n-6 PUFA decreased than the control. Serum alanine transaminase (ALT) increased in fish fed 70PBM-30DHI whereas haptoglobin upsurged in 70PBM-30FHI compared to 0PBM-0HI. There were no significant effects in the serum immune response between dietary treatments whilst serum and liver CAT activity were negatively impacted by 70PBM-30DHI. The 70PBM-30DHI induced hepatic steatosis whilst 0PBM-0HI and 70PBM-30FHI showed no obvious change in the liver. Skin mucosal barriers were impacted by 70PBM-30DHI whilst 70PBM-30FHI fed fish showed a similar response to 0PBM-0HI. The fish fed on 70PBM-30DHI showed a higher proportion of infection rate with Vibrio harveyi than 70PBM-30FHI but showed no variation with the control-fed fish. In summary, FHI larvae meal could be a good complementary protein source, particularly when replacing FM completely with insect-based proteins.

This study investigated the diversity of bacterial community in healthy and streptococcosis infected Nile tilapia (Oreochromis niloticus) to identify the primary causative agents associated with the disease using metagenomics, phylogenetic analysis and in vivo challenge test. A total of 24 fishes, both healthy and diseased were collected during summer from three different districts and six different ponds of Bangladesh. Alpha-beta diversity analysis of the next generation sequence data showed distinctly different (P

Integrated recirculating aquaculture systems (IRASs) were developed to overcome the problems of nutrient overloading and to address the issues of animal welfare in recirculating aquaculture systems. Barramundi (Lates calcarifer Bloch) (initial weight of 13.34 ± 0.01 g) were reared for 84 days in 12 (4 × 3 design) independent IRASs at four densities: 10.10, 12.98, 15.86 and 18.75 kg m− 3. Throughout the trial, the air was the only source of dissolved oxygen to the fish-rearing tank, and duckweed (Lemna minor Linnaeus) as a biofilter medium was used as an additional macrophytic crop in order to qualify as an IRAS. Therefore, each IRAS consisted of a fish-rearing tank, a waste-collection tank and a biofilter tank that housed the L. minor. At the end of the trial, blood samples were taken to determine levels of stress-related parameters (cortisol, glucose, lactate and whole-blood haemoglobin [Hb]) and thyroid hormones (thyroxine [T4] and triiodothyronine [T3]). In order to evaluate the acute stress response, the remaining fish were further exposed to elevated total ammonia, of which a portion was in the more toxic unionised form followed by blood analysis so as to determine the levels of stress-related parameters and thyroid hormones. The results demonstrated that a high stocking density of 18.75 kg m− 3 of barramundi significantly decreased the specific growth rate, increased the feed conversion ratio and altered plasma levels of total T4, total T3, cortisol, glucose, lactate and whole-blood Hb. Total plasma concentrations of T3 were inversely correlated with stocking densities, whereas total plasma T4 levels of juvenile barramundi were significantly higher when the juvenile barramundi were stocked at a higher density of 18.75 kg m− 3. These results also suggest that the growth suppression of the juvenile barramundi caused by a high stocking density might be associated with a decrease in circulating levels of thyroid hormones as a consequence of small but significant increased cortisol level. Therefore, a stocking density of lower than 18.75 kg m− 3 of barramundi is recommended for culturing in IRASs. Statement of relevance 1. An IRAS is developed to overcome the problem of nutrient overloading and animal welfare problems in recirculating aquaculture systems (RASs). 2. The study is required to establish an optimum stocking density requirement for juvenile barramundi in IRASs. 3. No studies have investigated the effects of stocking density on growth and physiological responses of juvenile barramundi species reared in integrated recirculating aquaculture systems (IRASs).

Very limited information is available on the relationship between dietary selenium (Se) and plant protein (PP) sources in carnivorous marine aquaculture species. Therefore, this study employed a 2 × 3 experimental layout to investigate the effects of lupin meal (LM) protein inclusion levels (0, 25 and 75%) and organic selenium (OS) levels (0 or 2 g kg− 1) on the growth, physiology and histopathology of juvenile barramundi (Lates calcarifer). The experimental diets (LM0, LM0 + OS, LM25, LM25 + OS, LM75 and LM75 + OS) were formulated on an isonitrogenous (48.8% crude protein) and isocalorific (20.6 MJ kg− 1 gross energy) basis. In the 60-day feeding experiment, final weight (FW), specific growth rate (SGR) and weight gain (WG) were improved by the supplementation of Se in LM-based diets. Fish fed diets containing Se had higher FW, SGR and WG compared with those fed diets lacking Se supplementation (P Statement of relevance While plant-based feed sources such as lupin meal have the potential to reduce the reliance on unsustainable wild fishmeal in aquaculture, such products may reduce the feed availability of selenium, an essential element for aquatic animals. We believe that the findings of this study are relevant to the general field of commercial aquaculture.

Seven isonitrogenous (47.0% crude protein), isolipidic (14.0% crude lipid) and isocaloric (22.0 MJ Kg−1 gross energy) diets were formulated and tested in a feeding trial to evaluate the efficacy of raw and enzyme-treated alga, Spirulina platensis (SP) to replace fishmeal (FM) on growth, digestibility, biochemical response and health status of juvenile barramundi, Lates calcarifer. The control diet had fishmeal as the main protein source and was progressively substituted with raw (RSP) or enzyme-treated SP (ESP) protein at 10%, 20%, and 40% of FM. Diets were fed in triplicated groups of barramundi with an initial body weight of 9.20 ± 0.3 g/fish, thrice a day for 8 weeks. The results showed that the weight gain (WG) and feed conversion ratio (FCR) were not negatively affected by the replacement of dietary ESP, while dietary 40% RSP level of FM significantly reduced (P .05) reduction of intestinal fold height, microvillus height, and thickness of muscular wall were recorded in fish fed RSP20, RSP40, and ESP40 diets than the control. The histopathological alterations in liver and muscle appeared in fish fed both ESP and RSP diets at 40% replacement of FM. Except for the fish fed 10% of RSP diet, all other fish, the exposure to transportation stress increased the plasma glucose levels although the plasma cortisol levels were not changed in various feeding levels. Overall, this study demonstrates that up to 20% RSP or 40% ESP unaffected the growth performance of juvenile barramundi while replacement of 40% FM with SP either raw or enzyme-treated impacted the health status in terms of the liver, muscle and intestinal morphology of fish.

Present study aimed to investigate the physiological and molecular response of 28-days starved marron (Cherax cainii), an economically important freshwater crayfish species. Thirty two marron were randomly distributed into two distinct groups in quadruplicated tanks with a density of 4 marron per tank. The feeding- group of marron was fed the marron basal diet on every day while the starved- group was deprived of feed for four weeks. The results showed a significant (P

This study aimed to investigate if the fermentation of sweet lupin, Lupinus angustifolius , increases the inclusion level of the lupin by replacing fishmeal content in the formulated diets of juvenile barramundi. Sweet lupin kernel was fermented by Lactobacilli (3.10 8 CFU/g) for 72 h to be used to replace fishmeal at 0%, 30%, 45%, 60%, and 75% of inclusion levels. The results showed that the fermentation of lupin significantly reduced the amount of anti-nutrients and improved the amino acid profile of the lupin. The growth rates of the juvenile barramundi were not adversely affected by the different inclusion levels of fermented lupin in the diets. There was an even significant increase in the final weight and length of the barramundi fed 45% and 60% fishmeal replacement diets. The survival rates were more than 93% in all dietary treatments. Feed conversion rates (FCR) were unchanged among the diets, except significantly higher FCR shown in 75% fishmeal replacement diet. The differences of protein digestibility among diets were not significant. However, hydrolyzed fat and phosphorus in the diets significantly increased ( p Lactobacilli improved the lupin’s nutritional quality, allowing higher inclusion level in barramundi diets.

Selenomethionine (SeMet) was supplemented to a fishmeal-based diet to investigate the toxic effects of excessive levels of dietary selenium (Se) in juvenile yellowtail kingfish ( Seriola lalandi ). For 10 weeks, the fish were fed one of five experimental diets; a basal diet containing 2.31 mg/kg of inherent Se or diets supplemented with SeMet to provide 4.91, 9.58, 15.43 or 20.87 mg/kg of Se. The results showed that the fish muscle proximate composition, feed conversion ratio and survival were not sensitive to dietary Se treatments; and no histopathological lesions were observed in heart and intestine tissues of the fish. The Se concentrations in liver and muscle tissues showed a strong linear positive relationship with the levels of Se in diets. Fish when fed the basal diet exhibited Se deficiency symptoms including myopathy, reduced feed intake, glutathione peroxidase activity and growth; whereas those fed the diets containing ≥ 4.91 mg Se/kg did not. While fish fed the 15.43 mg Se/kg diet did not show any toxic effects, the 20.87 mg Se/kg diet caused histopathological changes in liver and spleen as well as reduced feed intake, growth, haematocrit and hepatosomatic index, indicating Se toxicity. In conclusion, Se levels in liver and muscle tissues can be used as effective indicators of dietary Se exposure and dietary Se level between 15.43 and 20.87 mg/kg may be a threshold level in juvenile yellowtail kingfish.

Different forms of selenium (Se) were supplemented to a fishmeal-based diet to investigate the digestibility and bioavailability of Se in yellowtail kingfish (Seriola lalandi). Five groups of fish in triplicate were fed a basal diet (containing 3.31 mg/kg Se) either unsupplemented or supplemented with 2 mg/kg Se from selenite, selenocystine (SeCys), selenomethionine (SeMet) or Se-yeast for 6 weeks. The basal unsupplemented diet resulted in significantly lower weight gain, red blood cell glutathione peroxidase (GPx) and bactericidal activities than the supplemented diets. Muscle Se concentration was increased by Se supplementation from SeCys, SeMet or Se-yeast, but not selenite. There was no difference in GPx activity of fish fed with any supplemented diets. The bioavailability of Se from SeMet and Se-yeast was similar for all measurements. The most digestible sources of Se were from SeMet and Se-yeast, whereas the least was from fishmeal. Se from SeMet or Se-yeast produced more weight gain, higher Se accumulation in muscle tissues and bactericidal activity in yellowtail kingfish than Se from SeCys or selenite. This study shows that SeMet and Se-yeast are the most bioavailable sources of Se to yellowtail kingfish and are recommended to be supplemented to fishmeal-based formulated diets for yellowtail kingfish.

A feeding experiment was conducted to evaluate the effect of partial and complete replacement of freshwater shrimp ( Caridina nilotica ) (Roux) protein with boiled taro leaves [ Colocasia esculenta (L.) Schott] in diets of Nile tilapia ( Oreochromis niloticus Linnaeus) cultured in Kenya under semi-intensive conditions. Four formulated isonitrogenous test diets with protein levels of 23% were prepared in which taro leaf meal replaced the freshwater shrimp meal at 100% (D2), 67% (D3), 33% (D4) and 0% (D5). These diets were evaluated on the basis of growth performance of Nile tilapia, cost‐efficiency of the farming operations and water stability of the diets against a commercial diet (D1) and a test diet with no shrimp meal (D2). Though all the diets remained intact till they were ingested by the fish, the commercial diet had a significantly higher (P 2 ponds located at three different sites having 5 ponds each. Three randomly selected ponds received one experimental diet in such a way that each replicate was allocated to one site. All the ponds were initially stocked with tilapia fingerlings of 35.3 g and standard length 9.7 ± 0.2 cm at the rate of 1.4 fish/m 2 . At the end of the trial, the daily weight gain (DWG) and the total mean weight gain of tilapia fed with diets D1 and D2 were significantly higher (P 0.05) were observed in apparent food conversion ratio (AFCR), specific growth rate (SGR), and survival among any tilapia. Water quality parameters were similar among all ponds irrespective of diets received. At the final harvest, the size distribution showed that fish fed with D1 and D5 had a more uniform size distribution while those fed with D3 had a spread distribution. Cost benefit analysis indicated that D1 was the least cost effective (profit index = $2.75), while D2 (profit index = $12.20) was the most effective when taro leaves were sourced in situ . It was concluded that at 23% protein level, taro leaf protein could effectively replace shrimp meal protein in fertilized ponds without compromising growth performance, survival, and AFCR.

Integrated farming methods, where filter feeders are used to absorb suspended particles have been used for treating nutrients and particulate wastes from prawn culture system. This study investigated the effects of integrating varying stocking densities of blue mussels ( Mytilus e dulis ) with western king prawns ( Penaeus latisulcatus ) on the water quality and animals growth rates under a closed recirculating aquaculture system. The experiment was conducted using fifteen indoor recirculating systems which tested four different mussel and prawn stocking ratios (replicates of three) with a control of having prawns only. The four mussel densities and prawn biomass ratios were 0.25, 0.50, 1.00 and 2.00. Mussels in the system removed significant ( P

Integrating recirculating aquaculture systems with seaweeds is one of the strategies that can minimise wastes and risk of disease outbreaks. This study investigated the effect of integrating green seaweed ( Ulva lactuca ) with western king prawns ( Penaeus latisulcatus ) at varying stocking densities on the water quality, nutrient conversion rates and nutrient budget under closed recirculating culture system. The experiment was conducted using fifteen indoor tank recirculating systems and tested four different stocking ratios of prawns and seaweed with a control having prawns only. The four stocking ratios of seaweed and prawn biomass were 2, 4, 8 and 16 per tank. The mean concentrations of total ammonia nitrogen (TAN), NO 3 − –N and PO 4 3− –P in the prawn and seaweed tanks were significantly lower (P U. lactuca was highly efficient in removing the inorganic nutrients from the culture systems with TAN removal rate of 59–81% and PO 4 3− –P removal rate of 50–55%. Integrating seaweed with prawns did not significantly alter the specific growth rate (SGR) and survival rate of the prawns (P > 0.05). Ratio of C:P in seaweed tissues decreased with increasing seaweed stocking densities while C:N ratio showed an adverse trend. The nutrient conversion rate into total biomass (prawns plus seaweed) in the integrated systems was significantly higher at the highest seaweed stocking density (2.00 kg m − 2 ). Nutrient budget revealed that seaweed retained about 6.5–29.7% nitrogen and 1.6–13.5% phosphorus inputs while values for prawns were 28.0–31.9% and 13.5–14.6%, respectively. Seaweed also removed dissolved inorganic nitrogen effectively in the closed recirculating aquaculture system.

Effluent water from intensive prawn aquaculture systems typically has a high concentration of dissolved nutrients such as nitrogen and phosphorus. A study was conducted for 42 days to investigate the nutrient flow in a system where brown seaweed ( Sargassum sp. ) was integrated into western king prawn ( Penaeus latisulcatus) culture. Three treatments namely, western king prawn monoculture (5.48 ± 0.29 g), Sargassum sp. monoculture and seaweed/prawn integrated culture were tested for nutrient flow among feed, water and species cultured. The results showed that by integrating seaweed into prawn culture, the concentrations of total ammonium nitrogen (TAN), nitrite–nitrogen (NO 2 − ) and nitrate–nitrogen (NO 3 − ), dissolved inorganic nitrogen (DIN), total nitrogen (TN), phosphate (PO 4 3− ) and total phosphorus (TP) were significantly lower (p Sargassum sp. with western king prawn culture did not significantly alter the nitrogen and phosphorus conversion rates from feed into prawns (approximately 17.69–18.99 and 13.79–14.47%, respectively). The specific growth rate (SGR) and survival rate of the prawns in integrated treatment did not significantly differ (p > 0.05) from the prawn monoculture. The mean biomass of Sargassum sp. in integrated culture increased at the rate of 3.16 ± 0.74% g day −1 after 7 days of the study, which was significantly higher than in the monoculture system (5.70 ± 0.82% g day −1 ). The results suggest that integrating Sargassum sp. into western king prawn culture can benefit prawn farming by assisting in the maintenance of optimum water quality and thereby, reducing environmental impacts on surrounding areas.

The present study investigated the effects of dietary immunostimulants on the growth, survival and immune responses of juvenile western king prawns (Penaeus latisulcatus). The immunostimulants used were two prebiotics Bio-Mos® and β-1,3-D-glucan and two customised probiotics Pseudomonas synxantha and P. aeruginosa. The prawn juveniles (4.63 ± 0.39 g) were fed the formulated feed (control), supplemented with Bio-Mos® at 0.5%, β-1,3-D-glucan at 0.2% and a combination of two probiotics (105 CFU/mL at 50:50 v/v) at 20 mL/kg for 84 days of culture. The specific growth rate (SGR), survival and food conversion ratio (FCR) were higher in the prawns fed the immunostimulants than in the control. Although no significant effects on the SGR, survival and FCR were found when the prawns were fed either any prebiotics or probiotics, the higher survival was observed in the prawns fed the probiotics, while the higher SGR and lower FCR were observed in the prawns fed β-1,3-D-glucan, which had the most influence in increasing the surface structure of the prawn intestines. The healthier prawns showed the higher total haemocyte count (THC), the lowest clotting time and lowest bacterial load in the haemolymph when they were fed the probiotics. Continuous supplementation with the immunostimulants to the prawns for 84 days showed considerable improvement in the growth, survival and immune response of the prawns.

The growth inhibition ability of nine probiotic strains were investigated against 15 Vibrio spp. isolated from western king prawns, Penaeus latisulcatus (Kishinouye), and eight pathogenic Vibrio strains from other aquatic animals. Five different inhibition test methods such as bacteriocin-like inhibitory substance (BLIS), modified BLIS, disc-diffusion, well-diffusion and co-culture method were comparedin order toselect the most suitable probioticsfor usein the culture ofwestern kingprawns.The results showedthat the modified BLIS method was the most effective one for the selection of probiotics. Pseudomonas synxantha and P. aeruginosa were promising probiotics as theycaused a significantly higher (Pb0.05) growth inhibition of all theVibriospp. tested, withPseudomonas aeruginosa being more effective than P. synxantha. The growth inhibition zones were significantly greater (Pb0.05) when probiotics were grown on Marine Salt Agar (MSA) for three days before inoculating the plate with the Vibrio spp., but were not significantly different (PN0.05) when the probiotics and the Vibrio spp. were inoculated onto the plate at the same time. In the co-culture method, probiotics at a concentration of 10 3 CFU/mL allowed the Vibrio spp. (10 3 CFU/mL) to grow, but the Vibrio spp. cell densities never reached beyond their initial inoculum levels during the culture. At higher concentrations (10 5 –10 7 CFU/mL), the probiotics dominated the growth of the Vibrio spp. Therefore, administering a suitable concentration of probiotics and allowing growth and production of antimicrobial compounds before the addition of Vibrio spp. produced the best inhibition results. © 2007 Elsevier B.V. All rights reserved.

Western king prawns, Penaeus latisulcatus are a candidate species for culture in inland saline water. Western king prawn survival, growth, condition, osmo- and iono-regulation was studied when reared in potassium-fortified inland saline water for 202 days. PL40 prawns were stocked into three media in 250 L tanks: inland saline water with potassium fortified to 80% (IS80) of the marine water concentration, 100% (IS100) of the marine water concentration and marine water (MW). By the conclusion of the trial, survival was 53% in IS80, 64% in IS100 and 68% in MW. Mean prawn weight, total length, carapace length, condition factor and moult interval were significantly higher ( P P P > 0.05) in osmoregulatory capacity of prawns between various media. Serum Na + , K + , Ca 2+ and S concentrations were influenced by their concentration in the medium. Ca 2+ was the only major cation hyper-regulated and tended to be accumulated, while Mg 2+ was maintained at a much lower concentration in the serum than in the medium. Moisture contents in hepatopancreas, tail muscle and exoskeleton and organosomatic indices improved from IS80 to IS100 to MW. The lower growth rates and condition factors of prawns reared in potassium-fortified inland saline water suggests the presence of limiting factors other than potassium concentration. Western king prawns are stronger regulators of divalent cations than monovalent cations and the extra energy required to regulate ions in inland saline water may have been the major cause of lower growth rates.

Growth, osmoregulatory capacity, ionic regulation and organosomatic indices of black tiger prawn ( Penaeus monodon Fabricius, 1798) juveniles (2.6 ± 0.2 g mean initial weight) were studied for 28 days in two water types namely inland saline water fortified with 100% K + (ISW 100 ) as in ocean water (OW) and OW. Three different salinities (5, 25 and 45 ppt) of each water type were prepared. No water type or salinity affected the survival of juveniles. The highest specific growth rate (SGR) was observed at 25 ppt in OW (4.7 ± 0.2%/day) and ISW 100 (4.1 ± 0.1%/day). The serum osmolality was hyper-regulated and hypo-regulated in salinities below and above isosmotic points respectively. There was no significant difference ( P > 0.05) between osmoregulatory capacity (OC) of juveniles in ISW 100 and OW at any salinity or time, except at 25 ppt. Except exoskeleton moisture content (EM%) of the juveniles reared in OW, there were no significant differences ( P > 0.05) among any organosomatic indices of the juveniles reared in ISW 100 and OW. At 5 and 45 ppt, in both water types, serum Na + , K + and Ca 2+ concentrations were strongly regulated above and below isoionic points. However, the serum Mg 2+ concentration was reduced below the medium Mg 2+ concentrations at all salinities. The ability of P. monodon juveniles to regulate these ions in inland saline water (ISW) was improved by fortifying K + in ISW to a similar level as in OW. The present trial thus augments the importance of fortification of K + in ISW to a similar level as in OW for P. monodon culture.

The growth, survival, haemolymph osmolality and organosomatic indices of the western king prawn, Penaeus latisulcatus, (2.95±0.26 g mean initial weight), were measured when reared at 10, 22, 34 and 46 ppt salinity for 60 days. Mean final weight, total length and specific growth rate (SGR) of the prawns were highest at 34 ppt. Rearing at different salinities did not alter moult increments and intermoult periods of the prawns. One hundred percent mortalities were observed at 10 ppt. Survival was highest at 22 ppt and food conversion ratios were significantly lowest (P

A trial was conducted in 12 purpose-built, commercial, drainable, earthen ponds to evaluate the effect of fish and plant protein and lipid source on the growth, condition indices, and body composition of marron (Cherax tenuimanus). Juvenile marron (1.3 ± 0.28 S.E. g) at the stocking densities of three per square meter were fed for a period of 1 year with four different formulated isoenergetic practical diets (D1, D2, D3, and D4). Three of the test diets (D1, D2, and D3) were isonitrogenous whereas the fourth test diet (D4) was protein-free. Protein and lipid sources in D1 were from Lupin (Lupinus albus) whereas protein and lipid sources in D2 and D3 were from fish meal. Fish oil (3.5%) was added to D1, D3, and D4 whereas sunflower oil was added to D2 and D4 in order to make them isoenergetic. The four test diets were randomly allocated to three replicate ponds. The lack of protein in D4 did not significantly influence ( P > 0.05) the mean final weight andspecific growth rate of marron. Survival was low in all ponds (13.82–34.66%) but feeding with D4 resulted in a significantly (P Environmental variables, particularly temperature, nitrogen metabolites, and the natural productivity of the ecosystem, greatly influenced the nutritional requirements of the juvenile marron under culture.