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Background: Lesser sandeel (Ammodytes marinus) is widely distributed in North Sea ecosystems. Sandeel acts as a critical trophic link between zooplankton and top predators (fish, mammals, sea birds). Because they live buried in the sand, sandeel may be directly affected by the rapid expansion of anthropogenic activities linked to their habitat on the sea bottom (e.g., hydrocarbon extraction, offshore renewable energy, and subsea mining). It is, therefore, important to understand the impact of cumulative environmental and anthropogenic stressors on this species. A detailed description of the ontogenetic timeline and developmental staging for this species is lacking limiting the possibilities for comparative developmental studies assessing, e.g., the impact of various environmental stressors. Results: A detailed description of the morphological development of lesser sandeel and their developmental trajectory, obtained through visual observations and microscopic techniques, is presented. Methods for gamete stripping and intensive culture of the early life stages are also provided. Conclusion: This work provides a basis for future research to understand the effect of cumulative environmental and anthropogenic stressors on development in the early life stages of lesser sandeel. Key Findings: Lesser sandeel live buried in the sand and may be affected by the rapid expansion of anthropogenic activities linked to their habitat on the sea bottom. The ontogeny of this species has not been described.A timeline of changing morphological and physiological features of sandeel are reported in a comprehensive developmental map.Intensive culture techniques were developed that allowed for early life history of sandeel to be completed. This will support comparative developmental studies under controlled rearing conditions.The need for a mechanical stimulation during the hatching period to improve synchronicity, was identified as important factor in the intensive culture environment. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of dietary probiotic supplementation of Lactobacillus helveticus on growth, digestive enzymes, and hematological, biochemical, immune, and antioxidant parameters, as well as intestinal microbiota of rainbow trout (Oncorhynchus mykiss). Fish (35.46±0.9 g) were fed with different levels of dietary L. helveticus: control, 1 × 106, 1 × 107, 1 × 108, and 1 × 109 at high stocking density (80 kg m−3) for 60 days. Results indicated that growth performance significantly improved in probiotic supplemented fish (P<0.05). Digestive enzyme parameters revealed that supplementation could significantly increase amylase, protease, and lipase (P<0.05). The treated groups showed significant improvements in serum immune parameters including lysozyme (LYZ), alternative complement (ACH50), respiratory burst activity (RBA), and myeloperoxidase (MPO) (P<0.05). Total protein (TP), albumin (ALB), and globulin (GLO) increased in fish fed experimental diets (P<0.05). Lactate dehydrogenase (LDH) activity was significantly lower in fish fed dietary additives (P<0.05) while white blood cells (WBC), lymphocytes, neutrophils, hematocrit (Hct), red blood cells (RBC) were significantly enhanced (P<0.05). Fish fed with supplemented diets showed significantly enhanced antioxidant status, catalase (CAT) and superoxide dismutase (SOD). Malondialdehyde (MDA) content was significantly lower in fish fed dietary additives (P<0.05). Lactic acid bacteria (LAB) in the treatment groups were significantly increased (P<0.05). In conclusion, dietary supplementation of L. helveticus reduced detrimental effects of high stocking density on growth performance and immune response. It appears that L. helveticus can be recommended as a beneficial probiotic feed additive for rainbow trout. [ABSTRACT FROM AUTHOR]

Simple Summary: In intensive sheep farming, the temperature is an important indicator of the healthy growth of sheep. The key to ensuring the healthy growth of sheep in a stress-free environment is to grasp the changing trend in the sheep-house temperature in time and adjust in advance. In order to solve this problem, we use machine learning technology to establish a combined prediction model to accurately predict the temperature of the sheep barn. The result shows that the combined prediction model has good stability and high accuracy. Additionally, it can be extended to the prediction research of other environmental parameters of other animal houses, such as pig houses and cow houses, in the future. Too high or too low temperature in the sheep house will directly threaten the healthy growth of sheep. Prediction and early warning of temperature changes is an important measure to ensure the healthy growth of sheep. Aiming at the randomness and empirical problem of parameter selection of the traditional single Extreme Gradient Boosting (XGBoost) model, this paper proposes an optimization method based on Principal Component Analysis (PCA) and Particle Swarm Optimization (PSO). Then, using the proposed PCA-PSO-XGBoost to predict the temperature in the sheep house. First, PCA is used to screen the key influencing factors of the sheep house temperature. The dimension of the input vector of the model is reduced; PSO-XGBoost is used to build a temperature prediction model, and the PSO optimization algorithm selects the main hyperparameters of XGBoost. We carried out a global search and determined the optimal hyperparameters of the XGBoost model through iterative calculation. Using the data of the Xinjiang Manas intensive sheep breeding base to conduct a simulation experiment, the results show that it is different from the existing ones. Compared with the temperature prediction model, the evaluation indicators of the PCA-PSO-XGBoost model proposed in this paper are root mean square error (RMSE), mean square error (MSE), coefficient of determination (R2), mean absolute error (MAE) , which are 0.0433, 0.0019, 0.9995, 0.0065, respectively. RMSE, MSE, and MAE are improved by 68, 90, and 94% compared with the traditional XGBoost model. The experimental results show that the model established in this paper has higher accuracy and better stability, can effectively provide guiding suggestions for monitoring and regulating temperature changes in intensive housing and can be extended to the prediction research of other environmental parameters of other animal houses such as pig houses and cow houses in the future. [ABSTRACT FROM AUTHOR]

The calanoid copepod Eurytemora pacifica is the most abundant species of zooplankton inhabiting waters in the western and southern bays of Korea during winter and spring. In this study, we sought to determine the effects of four photoperiodic regimes (0L:24D, 10L:14D, 12L:12D, 14L:10D) on the egg clutch size, hatching success, and naupliar production of E. pacifica. We found that photoperiod had a significant effect on E. pacifica clutch size, with egg production being the highest and lowest under photoperiods of 12L:12D and 14L:10D, respectively. In terms of hatching success, the highest hatch rate (73.4%) was obtained at 0L:24D, whereas eggs derived from females exposed to a 14L:10D photoperiod failed to hatch. Furthermore, naupliar production was found to be highest at 12L:12D (35.1 ± 6.5 nauplii female−1 day−1). Our findings indicate that the clutch size, hatchability, and naupliar productivity of E. pacifica can be significantly influenced by photoperiodic conditions, with a notably pronounced decline in hatching success and naupliar production occurring in response to a 14L:10D photoperiod. These observations provide valuable insights into the reproductive biology of E. pacifica over a wide photoperiodic range and can potentially contribute to the culturing of this copepod as a source of live larval feed in aquaculture hatcheries. [ABSTRACT FROM AUTHOR]

The present study examined the effects of different protein concentrations on growth of juvenile common carp kept in 15 fiberglass ponds (0.5 × 2 × 2 m) under intensive culture system involving 5 treatments and 3 replications, based on the following raw protein contents (24.22, 26.15, 28.32, 30.31, 33.29%) included in the fish diet for a period of 60 days and with a water temperature ranging 22-31oC, and dissolve oxygen level of 5.1-7.3 mg/L to determine diet formulation ensuring an optimum growth performance. Each rearing pond was introduced with 250 pieces of juvenile fish (4 ± 0.66 g) amounting to an average of 1 kg fish biomass. The results indicated that juveniles receiving protein levels of 28.32% and 26.15% had the highest body weight, specific growth rate, weight gain percentage and protein yields (p≤0.05). In addition, the feed conversion ratio related to these two diets showed significant decline (p≤0.05). The condition factor and survival rate remained the same across all treatments (p≥0.05). The study revealed that the protein increment ratio of up to 28.15% in the diet contributed to the increased growth indices among juvenile common carp and concentrations beyond that did not lead to any effective increase in fish growth.

Intensive catfish [Clarias gariepinus(Burchell, 1822)] cultivation produces organic waste that decreases water quality. The aquaponics system utilizes fish waste for plant growth to produce useful and economical products. This study aims to analyze and evaluate the best density of Mexican sword plant/water Jasmine [Echinodorus palaefolius (J. F. Macbr.)] in reducing waste from intensive catfish aquaculture. The research method used a completely randomized design (CRD) with four treatments with three replications. A plastic tub with a size of 38 cm × 12 cm × 30 cm filled with sand was used for plant media, while for catfish rearing containers, a 70 L tub with a water volume of 40 L was used. The fish used in this experiment were catfish fry with a size of 7 cm ± 0.8 cm, a weight of 5.14 g ± 0.45 g, with a stocking density of one fry per liter. Catfish fry were fed with floating pellet feed of 30 % protein content, and the feeding was done at satiation. The treatments were T1 = without plants, T2 = 150 g m–2 plants, T3 = 250 g m–2 plants, and T4 = 350 g m–2 plants. Furthermore, all data were analyzed through ANOVA (One-way analysis of variance) and the Duncan’s multiple range test to measure significant variations among the treatments using SPSS (version 17, USA). The results revealed that T4 was the best treatment in terms of nutrient removal efficiency of TAN, NO2, NO3, and PO4 at the rate of 23.80 %, 48.19 %, 52.99 % and 26.11 %, respectively. Moreover, growth performances of fish fry fed diet in T4 also were significantly (P < 0.05) higher than other fishes of different treatments. Regarding these findings, E. palaefolius could work well to maintain water quality during C. gariepinus cultivation and even accelerated C. gariepinus growth at the end of the period. [ABSTRACT FROM AUTHOR]

The concept of continuous egg and adult separation was studied to evaluate the possibility of cultivating the copepod Acartia tonsa at high density (> 2.5 adults mL−1). First experiment: Densities of 5, 10, 15, 30, and 45 adults mL−1 were evaluated. For this, eggs spawned were allowed to settle quickly, harvested, and counted to determine the specific and relative egg production (SEP and REP, eggs female−1 day−1 and eggs mL−1 day−1, respectively). Second experiment: Mature females were spawned on slides to observe the shape of the freshly spawned eggs. Third experiment: respiratory rate under four corporal velocities in the filter system were evaluated (57, 115, 173 and 231 PL min−1; PL, prosome length), corresponding to four water exchange rates (50, 100, 150 and 200 volumes day−1). Fourth experiment: A high-density (7 adults mL−1) prototype based on continuous egg separation was designed and compared with daily egg harvest for siphon (control system). The specific egg production (SEP, egg female−1 day−1) and relative egg production were determined (REP, eggs mL−1 day−1). The SEP decreased with culture density (p 2.5 mL−1), which was confirmed by higher REP in the prototype (100 eggs mL−1 day−1) than in the control system. This study contributes to intensive A. tonsa culture; a superior density of 5 mL−1 is possible with a high water exchange rate and careful egg harvesting.

Too high or too low temperature in the sheep house will directly threaten the healthy growth of sheep. Prediction and early warning of temperature changes is an important measure to ensure the healthy growth of sheep. Aiming at the randomness and empirical problem of parameter selection of the traditional single Extreme Gradient Boosting (XGBoost) model, this paper proposes an optimization method based on Principal Component Analysis (PCA) and Particle Swarm Optimization (PSO). Then, using the proposed PCA-PSO-XGBoost to predict the temperature in the sheep house. First, PCA is used to screen the key influencing factors of the sheep house temperature. The dimension of the input vector of the model is reduced; PSO-XGBoost is used to build a temperature prediction model, and the PSO optimization algorithm selects the main hyperparameters of XGBoost. We carried out a global search and determined the optimal hyperparameters of the XGBoost model through iterative calculation. Using the data of the Xinjiang Manas intensive sheep breeding base to conduct a simulation experiment, the results show that it is different from the existing ones. Compared with the temperature prediction model, the evaluation indicators of the PCA-PSO-XGBoost model proposed in this paper are root mean square error (RMSE), mean square error (MSE), coefficient of determination (R2), mean absolute error (MAE) , which are 0.0433, 0.0019, 0.9995, 0.0065, respectively. RMSE, MSE, and MAE are improved by 68, 90, and 94% compared with the traditional XGBoost model. The experimental results show that the model established in this paper has higher accuracy and better stability, can effectively provide guiding suggestions for monitoring and regulating temperature changes in intensive housing and can be extended to the prediction research of other environmental parameters of other animal houses such as pig houses and cow houses in the future.

The calanoid copepod Acartia ohtsukai predominates the estuarine and coastal waters of East Asia during summer. Its occurrence characteristics confer it with good potential as live prey for fish larvae through mass culture. To investigate the effect of temperature and salinity combinations on its egg production rate (EPR), hatching success (HS), and mortality rate, experiments were undertaken and repeated three times for combinations of five temperatures (10, 15, 20, 25, and 30°C) and seven salinities (10, 15, 20, 25, 27, 30, and 33 psu). EPR and HS were highest at temperatures of 25 and 30°C, respectively, with a salinity of 27 psu. Mortality rate was highest at 10°C in almost all salinity gradients, whereas it was lower at water temperature and salinity ranges of 20–30°C and 20–30 psu, respectively. These findings indicate that A. ohtsukai can inhabit wide ranges of water temperatures and salinities, and that the optimized condition for mass culture is a combination of water temperature of 25°C and salinity of 27 psu.

Objective. To evaluate the growth and survival of Cryphiops caementarius in coculture with Oreochromis niloticus at different densities. Materials and methods. Male prawns (5.86 cm and 7.65 g) and reverse tilapia fingerlings (5.65 cm and 2.61 g) were used. Nine aquariums (55 L) were used. Six containers were installed in each aquarium, where one prawn was stocked per container (32 prawn/m2), and in the remaining water, tilapia was stocked at densities of 100, 200 and 300 fish/m3. Balanced feed was used. The daily ration for prawns was 6% and for tilapia, it was 5% of the total biomass. The experiment lasted 90 days. Results. In prawns, the length (6.46 cm), weight (9.37 g), percentage gains in length (10.01% at 10.45%) weight (19.24% a 25.41%), and survival (88.89% to 94.44%) were similar (p<0.05) between treatments. The effect of molting death syndrome is discussed. In tilapia, the length (9.25 cm), weight (12.90 g), absolute growth rate (0.040 cm/day; 0.114 g/day), specific growth rate (0.55% length/day; 1.759% weight/day) and percentage gain (64.21%; 389.48%) were greater (p<0.05) at 100 and 200 fish/m3. Tilapia survival was similar (86.11%) between treatments. Conclusions. Prawn growth and survival were affected by molt death syndrome but not by the presence of tilapia in the system. In contrast, greater growth of tilapia was obtained with 100 fish/m3, although survival was similar between treatments. [ABSTRACT FROM AUTHOR]

The increase in overfishing and pollution in Pátzcuaro Lake, Michoacán, México, has generated a severe problem in the endemic species that live there; especially the Chirostoma estor estor that has been threatened. A computational model has been developed for the evaluation of water quality in freshwater intensive farming tanks to contribute to the conservation efforts of this species. The proposed model uses a fuzzy inference system weighted through a rule categorization process. Five parameters were selected for the analysis: dissolved oxygen, pH, temperature, total ammonia, and non-ionized ammonia, because they represent the primary set of parameters that affect the water quality and health of the species studied. The measurements were made on the Chirostoma farms, and different situations were studied to define weights of importance according to the situations of negative impact on water quality. The rules are maximized or minimized with those weights and then integrated into a final score (Chirostoma Water Quality Index (CWI). The CWI values have been compared with NSF and CCME. It is noted that the CWI values are more representative of the actual state of water quality for the Chirostoma estor estor. This is because the weighted fuzzy logic approach is sensitive to all parameters and can identify harmful situations by using the rules. CWI can be a useful tool for monitoring and managing the quality of tanks, as it provides helpful information to prioritize and maintain water quality, and this in turn favors the growth, reproduction, and preservation of the species.

Bicarbonate ions are the primary source of inorganic carbon for autotrophic organisms living in aquatic environments. In the present study, we evaluated the short-term (hours) effects of sodium bicarbonate (NaHCO3) addition on the growth and photosynthetic efficiency of the green algae Chlorella sorokiniana (211/8k). Bicarbonate was added to nonaxenic cultures at concentrations of 1, 2, and 3 g L−1 leading to a significant increase in biomass especially at the highest salt concentration (3 g L−1) and also showing a bactericidal and bacteriostatic effect that helped to keep a reduced microbial load in the algal culture. Furthermore, bicarbonate stimulated the increase in cellular content of chlorophyll a, improving the photosynthetic performance of cells. Since microalgae of genus Chlorella spp. show great industrial potential for the production of biofuels, nutraceuticals, cosmetics, health, and dietary supplements and the use of bicarbonate as a source of inorganic carbon led to short-term responses in Chlorella sorokiniana, this method represents a valid alternative not only to the insufflation of carbon dioxide for the intensive cultures but also for the production of potentially bioactive compounds in a short period. [ABSTRACT FROM AUTHOR]

Microalgae biomass is a source of a wide range of high commercial value compounds such as proteins, carotenoids, lipids and polysaccharides that have potential applications in several biotechnological processes. This study evaluated the influence of two different illuminated surface-to-volume-ratios (S/V) on the growth in cultivation of Scenedesmus obliquus in a thin-layer cascade system (TLC). Two S/V ratios (80 m−1 and 60 m−1) were used, corresponding to water columns of 0.5 cm and 1.0 cm, respectively. The cultures were compared in terms of the maximum biomass attained, volumetric and area productivities, photosynthetic efficiency, and CO2 fixation into biomass. The maximum biomass achieved was 20.14 g L−1 in SV80 cultures while the SV60 treatments attained 14.60 g L−1, with a maximum volumetric productivity of 2.42 and 1.85 g L−1 day−1, respectively. The culture with lower S/V was more efficient in relation to CO2 fixation, reaching 62% of the total carbon offered in comparison to the higher S/V (54%). Concerning the incident energy in the daylight period, both treatments presented similar photosynthetic efficiency values. [ABSTRACT FROM AUTHOR]

We evaluated the relationship of stocking density to survival, growth performance and fin condition of European perch Perca fluviatilis with hand feeding and self‐feeders. Hand‐fed perch (body weight 19.1 ± 5.1 g and total length 107 ± 9 mm) were reared at 0.5, 1.0, 1.5 and 2.0 fish/L. Self‐feeding perch (body weight 25.4 ± 3.9 g and total length 128 ± 7 mm) were reared at stocking densities of 0.6, 1.0 and 1.4 fish/L. Pond‐reared perch served as a comparison group for fin damage assessment. We found no differences in survival rate among stocking densities with either feeding method. Hand‐fed fish displayed the highest weight gain and SGR at stocking density of 0.5 fish/L. The self‐feeding fish showed a non‐linear association of weight gain with stocking density with the highest growth at 1.0 fish/L. Fin length was noticeably greater in pond‐reared fish compared with RAS‐reared fish regardless of feeding method. In both experiments, fin length relative to standard length showed a negative relationship with stocking density, with pectoral fins showing the greatest effect. Fin condition deteriorated with increasing stocking density, and growth was highest at 0.5 and 1.0 fish/L in hand‐fed and self‐feeding fish, respectively. [ABSTRACT FROM AUTHOR]

Aquaculture is a productive activity in economic growth due to market productivity which supports many Ecuadorian communities. However, exotic species has been the basis of this activity without considering the endemic and mega-diverse component of Ecuador. On the other hand, current aquaculture systems use a lot of water, generating discharge of nitrogen and phosphorus, causing a negative impact on natural watersheds. The present investigation focused on the diversification of aquaculture production and environmental care, through the polyculture of tilapia and river prawn, in a Biofloc system, which allows reducing the use of water, space, and food, taking advantage of all the nutrients of the aquatic environment without generating pollutant residues, from a carbon-nitrogen ratio of 20:1. The research project was developed under laboratory conditions at 2.728 amsl, for 8 weeks in pre-breading stages. Two factors were established in the study: type of culture (monoculture and polyculture) and production systems (traditional and biofloc), with three replicates. In the Biofloc system, the environmental variables such as temperature, pH, and oxygen did not show any significant differences between treatments (p=0.05), while conductivity and total suspended solids increased during the test, and the nitrification processes stabilized at day 28 with values of 0.06±0.01 and 0.35±0.09 ppm in ammonium and nitrite respectively. The bacterial load was higher in the Biofloc system (113.66x103 CFU/ml) with predominance of Bacillus sp. and Pseudomonas sp. The bioflocs showed greater volume in polyculture (17.62 ml/L) and 26% of protein. Under these considerations, the best productive performance was detected in the Biofloc polyculture with a total productivity of 142.86g/m2 (p=0.05). Therefore, diversification of species, types and culture systems are viable for aquaculture in Ecuador, generating an interaction between the chemical and biological components, allowing productive processes to be sustainable. [ABSTRACT FROM AUTHOR]

Bicarbonate ions are the primary source of inorganic carbon for autotrophic organisms living in aquatic environments. In the present study, we evaluated the short-term (hours) effects of sodium bicarbonate (NaHCO3) addition on the growth and photosynthetic efficiency of the green algae Chlorella sorokiniana (211/8k). Bicarbonate was added to nonaxenic cultures at concentrations of 1, 2, and 3 g L−1 leading to a significant increase in biomass especially at the highest salt concentration (3 g L−1) and also showing a bactericidal and bacteriostatic effect that helped to keep a reduced microbial load in the algal culture. Furthermore, bicarbonate stimulated the increase in cellular content of chlorophyll a, improving the photosynthetic performance of cells. Since microalgae of genus Chlorella spp. show great industrial potential for the production of biofuels, nutraceuticals, cosmetics, health, and dietary supplements and the use of bicarbonate as a source of inorganic carbon led to short-term responses in Chlorella sorokiniana, this method represents a valid alternative not only to the insufflation of carbon dioxide for the intensive cultures but also for the production of potentially bioactive compounds in a short period.

One of the main bottlenecks for the exploitation of microalgae is the low biomass concentration of the cultures: high harvesting costs and large cultivation area are always required. This bottleneck is partly due to a low light availability along the optical path of photobioreactors. An ultra-thin flat photobioreactor (UFP) (3 mm thickness) was proposed to increase both biomass concentration and productivity. The performance of the UFP was investigated: the effects of incident light intensity - from 50 and 1000 μmol Photons  m −2  s −1 - on cell growth, photosynthesis rate, and biochemical composition of Chlorella sorokiniana were characterized. The maximum microalgal concentration and the maximum areal productivity were 24 kg m −3 and 1.34 g m −2  h −1 , respectively. The cell specific growth rate reached 0.1 h −1 at 1000 μmol m −2  s −1 . The biochemical composition of the microalgal biomass changed with the light irradiance. Protein content increased from 35 up to 53% of DW with increasing the light intensity. The concentration of storage compounds, such as starch and lipids, decreased from 30 to 16% and from 30 to 10%, respectively, with increasing the light intensity. A limit in the maximum biomass concentration achievable was identified. Several hypotheses have been discussed. A light transfer model was applied to assess the presence of light limitation. Other hypotheses were analyzed in depth and the most feasible explanations were found to be a) the damage to the photosystem when exposed for long period to continuous and high light irradiances, b) nutrient limitation due to salt precipitation or c) gas-liquid transfer of the CO 2 . Finally, benefits and drawbacks of the ultra-thin culture system were discussed. [ABSTRACT FROM AUTHOR]

Abstract: Whiteleg (Litopenaeus vannamei) and black tiger (Penaeus monodon) shrimp are the most common farm‐based shrimp species cultured in Vietnam, but there have been few studies of intensive whiteleg shrimp production. The objectives of this study were to describe production characteristics and to identify factors associated with yield in intensive shrimp production systems in Vietnam. This study included data from shrimp farms in four Vietnam provinces, collected from mid‐2014 to early 2016. The data included key production characteristics, such as length of production cycle, number and quality of postlarvae (PL) stocked, feed intake, production yield (kg/m2), harvest size (shrimp/kg), average weight and water quality measurements for some of the crops. We report descriptive statistics for the production parameters and findings from two linear mixed models describing the associations of these parameters with two outcomes: production yield and average weight of shrimp. The average stocking density for the 846 crops included in the dataset was 109 PL/m2, average length of production cycle was 92 days, and average production yield was 1.15 kg/m2. The shrimp gained 0.2 g per day, on average, and consumed an average of 0.17 kg of feed, daily/1,000 PL stocked. The linear mixed models indicated that stocking density, stocking month and region were the main predictors for production yield, while water temperature 4 weeks prior and PL quality were the main predictors for the average weight of shrimp, after accounting for the length of production cycle. This study describes baseline production parameters for whiteleg shrimp production in Vietnam. [ABSTRACT FROM AUTHOR]

This study investigated the effects of different dissolved carbon dioxide (CO 2) concentrations (400, 700, and 1000 ppm) on the growth and vertebral column formation of hybrid tiger grouper × giant grouper (TG × GG) in their advanced larval stage under controlled laboratory conditions for 12 weeks. Growth parameters, including specific growth rate (SGR), survival rate, food consumption (FC), and food conversion rate (FCR), were calculated at the end of the experiment. Vertebral column formation was analysed using X-radiography and osteology methods. The results showed that all growth parameters were significantly affected by CO 2 concentration, with the best performances observed under 400 ppm CO2. The highest statistically significant (p < 0.05) SGR, survival rate, and FC were observed under 400 ppm CO 2 , whereas the lowest was observed under 1000 ppm CO2. The lowest FCR (0.40, p < 0.05) was observed in 400 ppm CO 2 and the highest was observed at 1000 ppm CO 2 (0.59, p < 0.05). Furthermore, larvae without vertebral column malformations were observed in 400 ppm CO 2 , while larvae with small angles of kyphosis were observed in 700 ppm CO 2 , and larvae with kyphosis, lordosis, and vertebral compression were observed in 1000 ppm CO 2. Only six spine measurements out of 31 obtained under different CO 2 concentrations were significantly different (p < 0.05). Overall, the results suggest that CO 2 concentration plays a crucial role in the growth and vertebral column formation of TG × GG in their advanced larval stage. The optimal CO 2 concentration for the aquaculture of TG × GG in their advanced larval stage was found to be 400 ppm or lower. This study highlights the importance of maintaining optimal CO 2 concentrations to enhance the growth and health of fish in aquaculture systems. • Ocean acidification harms marine hybrid larvae - tiger grouper × giant grouper (TG × GG). • 1000 ppm CO 2 results in poor growth, weight, survival, and food conversion. • Deformities in vertebral columns at 1000 ppm CO 2 ; normal at 400 ppm CO 2. • Study offers direction for further research on marine larvae in high CO 2 conditions. [ABSTRACT FROM AUTHOR]

Freshwater macroalgae are an attractive treatment option for waste streams that have very high concentrations of nutrients. However, the long water residence times required in these scenarios will result in carbon becoming a limiting nutrient that negatively impacts the rate of biomass productivity and, subsequently, the potential for nutrient uptake. This study examined how the rate of carbon supplementation influenced the biomass productivity of Oedogonium intermedium , during both winter and summer periods in high rate algal ponds (HRAPs) maintained under batch conditions. We also examined the novel use of molasses as a source of carbon for intensive algal cultures and compared its effect on biomass productivity to that of CO 2 gas. Oedogonium intermedium responded positively to carbon supplementation from both molasses and CO 2 gas, with biomass productivity increasing as the rate of carbon supplementation increased. In cultures with no carbon supplementation, the average productivity of O. intermedium was 2.2 (± 0.8) g m − 2 day − 1 , and a maximum of 17.3 g m − 2 day − 1 and 20.8 g m − 2 day − 1 during summer when carbon was supplemented through the addition of molasses and CO 2 , respectively. The optimal rate of carbon supplementation was 0.06 g of carbon per liter (g (C) L − 1 ) in winter and 0.08 g (C) L − 1 during summer. The addition of an exogenous source of carbon resulted in a decline in the culture pH and increased the availability of the dissolved inorganic carbon (DIC) pool and subsequently, carbon uptake by the algae. This study has identified a novel method to supplement carbon to algal cultures, where the waste residue from the sugar industry can be used as viable source of inorganic carbon. Importantly, we have demonstrated that O. intermedium can be cultivated in HRAPs without requiring a high rate of water exchange, providing that its requirements of DIC are satisfied. [ABSTRACT FROM AUTHOR]

The present study explored the susceptibility of Puntius pulchellus subadults to Lernaea cyprinacea infection subsequent upon their first introduction to an intensive culture system that had a previous history of Lernaea infection and evaluated the efficacy of doramectin against the parasite. All the P. pulchellus introduced to the culture pond got infected demonstrating 100 % susceptibility of this species to Lernaea infection. Pathological changes caused by the parasite as evidenced by the extensive hemorrhage and tissue necrosis of the host at the point of parasite attachment was most severe in P. pulchellus. On the contrary, among the fish species already present in the pond and were previously exposed to the infection before the start of the present study, only Labeo fimbriatus developed mild to moderate infection. Cirrhinus mrigala, Ctenopharyngodon idella and Cyprinus carpio from the same culture pond did not develop Lernaea infection. Doramectin administration at 1 mg/kg b.wt. of fish incorporated in feed and given orally for 10 days or by a single intramuscular injection at 200 μg/kg b.wt. was found to be effective in controlling L. cyprinacea adult parasite infection in P. pulchellus. Doramectin hastened healing of the wounds caused by L. cyprinacea and did not cause any noticeable adverse reactions or toxicity to the fish host during the present study. In conclusion, P. pulchellus was observed to be highly susceptible to L. cyprinacea upon its first exposure to the infective stages of the parasite and a single intramuscular injection of doramectin at 200 μg/kg b.wt. was more effective than oral administration of the drug in controlling L. cyprinacea infection. [ABSTRACT FROM AUTHOR]

Growth and survival rates (specific growth rate - SGR; survival rate - S) of Barbus barbus L. were recorded in captivity during three years from the larval period (final body weight - W = 0.2 ± 0.03 g; SGR = 13.6 ± 1.1%/day and cumulative survival - S = 76.0 ± 2.5%) to the first reproductive season (W = 62.55 ± 13.5 g; SGR = 0.89 ± 0.05%/day; S = 59.3 ± 1.5%). Final body size and SGR were compared between both sexes. Females reached the significantly higher growth rate (SGR = 0.84 ± 0.01%/day) compared to males (SGR = 0.77 ± 0.01%/day). Early puberty was observed in 17 and 32 months old males and females, respectively. Multi-stripping activity was found out in both sexes during the first reproductive season. In total, 20%, 25.8%, 30.3%, 14.6% and 9% of females were stripped once, twice and three, four and five times, respectively. But all males produced sperm during the entire reproductive season. The highest and the lowest egg production was recorded in the middle (April) and at the beginning (March) of the reproductive season (2155 ± 925 vs. 1279 ± 298 eggs per stripping). The highest and the lowest sperm production was observed at the beginning (March) and at the end (May) of the reproductive season (7.9 ± 0.08 × 109 vs. 1.9 ± 0.06 × 109 per stripping).

Higher rates of production per unit area, avoiding or minimizing significant environmental damages, is a challenge for aquaculture to contribute with an ascendant demand for food due to the increase in world population. The present study assessed the hatchery performance of Litopenaeus vannamei between the mysis 1 and postlarva 5 stages, in a zero-exchange biofloc system under 12.5:1 fixed C:N ratio with dextrose in four stocking densities: 200, 250, 300 and 350 larvae per liter (D200, D250, D300, D350 respectively). Water quality and performance parameters were compared among treatments. The mean values of the evaluated water quality parameters were appropriate for this production stage in all treatments. Fertilization with dextrose efficiently controlled ammonia levels not reaching the average concentrations considered toxic for the specie. Lower values of pH and higher values of volatile solids were finding in D350. There was no difference between groups in means of survival and dry weight of postlarva 5. Therefore, the use of biofloc systems without water exchange with dextrose as a carbon source in 12.5:1C:N ratio resulting in adequate production indexes and water quality during the mysis 1 to postlarva 5 hatchery phase of L. vannamei . Based in these results the density limit to a viable BFT hatchery was not reached. [ABSTRACT FROM AUTHOR]

Se evaluó el cultivo de dorada (Brycon sinuensis) en jaulas flotantes durante 180 días. Se determinó el crecimiento mediante la ganancia en longitud, ganancia en peso, tasa de crecimiento específico, sobrevivencia final, biomasa total, factor de condición y factor de conversión alimenticia. Se sembraron 816 juveniles con talla promedio de 17.8 cm de longitud total y peso promedio de 78.7 g, en cuatro tratamientos con densidad de siembra de 25 peces/m3 y tres réplicas cada uno. Las dietas balanceadas (proteína bruta) suministradas fueron: tratamiento 1: 20%; tratamiento 2: 32%; tratamiento 3: 28%; y tratamiento 4: 24%, con diseño experimental completamente aleatorio. Se puede afirmar que la dorada consumió las dietas de origen vegetal de igual manera que las de origen animal, sin embargo la dieta del 28% de proteína bruta (tratamiento 3) muestra los mejores resultados, sin diferencias significativas entre tratamientos (p>0.05). En todos los trabajos anteriores, la ganancia en peso diaria fue baja, pero mejor que las obtenidas en esta investigación. Mientras que el rendimiento en biomasa fue mayor que los reportados para cultivos en estanques, para todos los tratamientos en este estudio fue muy bajo.Dorada´s culture (Brycon sinuensis) in floating cages during 180 days was evaluated. The increment in length, increment in weight, specify growth rate, final survival, total biomass, condition factor and nutritional conversion factor were determinated. 816 fishes with mean length of 17.8 cm total length and mean weight of 78.9 g were stocked in four treatments with stocking densities of 25 fishes/m3 and three replica each one. The balanced diets (gross protein) supplied were: treatment 1: 20%, treatment 2: 32%, treatment 3: 28%, and treatment 4: 24%, with experimental design random completely. Can be affirmed that the dorada fed the diets of vegetable origin as equal way than those of animal origin, although the diet of 28% gross protein (treatment 3) shows best perfomance, without significant differences between treatments (p>0.05). In other works with this species, the daily gain in weight was low, but better than the one obtained in this work; whereas the biomass yield was greater than the biomass yield reported for ponds cultures, the results of this study were very low

Bacterial inorganic nitrogen control using carbon:nitrogen ratio (C:N) manipulation is a tool for aquaculture systems. The present study assessed the hatchery performance of Litopenaeus vannamei between the mysis 1 and postlarvae 5 stages in a zero-exchange biofloc system under different C:N fertilization levels (10:1, 12.5:1 and 15:1) with dextrose. Water quality, performance parameters and water microbiology were compared among treatments. The mean values of the evaluated water quality parameters were appropriate for this production stage. Fertilization with dextrose efficiently controlled ammonia levels, which did not reach the average concentrations considered toxic for the species. In the 10:1 C:N ratio treatment, the levels of ammonia started to increase early and showed significantly higher levels from the third to the last experimental day. There was no difference among groups in means of survival (>76%) and dry weight (0.26 mg) of L. vannamei production parameters and water quality were maintained without water exchange using a biofloc system supplemented with dextrose. Therefore, the use of biofloc systems without water exchange with dextrose as a carbon source in C:N ratios of 10:1, 12.5:1 and 15:1 results in both adequate production indexes and water quality during the misis 1 to post-larvae 5 hatchery phases of L. vannamei . However, the ratios of 12.5:1 and 15:1 keep lower levels of ammonia. [ABSTRACT FROM AUTHOR]

Foi avaliado o desempenho de juvenis de pirarucu em criação intensiva em viveiros escavados. Oitenta e cinco peixes com peso médio inicial de 133,3 ± 1,3g foram estocados em dois viveiros de 120m² cada (densidade de 1 peixe/3m²), com profundidade média de 1m e alimentados duas vezes ao dia (9:00 e 14:00h) com ração extrusada para peixes carnívoros contendo 40% de proteína bruta. Foi verificado diariamente o consumo de ração, enquanto mensalmente os peixes foram amostrados para a realização de biometrias com a finalidade de verificar seu desempenho em peso e comprimento. Após 12 meses de cultivo os peixes atingiram peso médio de 7,0 ± 1,1kg, comprimento total de 88,2 ±6,4cm, com conversão alimentar de 1,5 e produtividade de 2,5kg/m². Estes resultados mostram o grande potencial do pirarucu para a piscicultura intensiva na Amazônia.Growth performance of pirarucu cultivated under intensive production system in excavated ponds was evaluated. Eighty five fishes with an initial mean weight of 133.3 ± 1.3 g were stocked into two 120m² ponds and were fed extruded diets with 40% crude protein twice a day (0900 and 1400 h). Feed consumption was recorded daily, while fish were sampled every month to check for body weight gain and growth performance. After 12 months mean weight was around 7.0 ± 1.1kg, total length was 88.2 ± 6.4 cm, feed conversion ratio were 1.5 and productivity 2.5kg/m². These results have shown that pirarucu presents a great potential when raised under intensive aquaculture systems.

We assessed the hatchery performance of Litopenaeus vannamei between the mysis1 and postlarva 5 stages, in a zero-exchange biofloc system. Two sources of organic carbon (molasses and dextrose) were evaluated and water quality, zootechnical parameters, microbiology, and water consumption during production were compared between carbon-supplemented and control groups. The mean values of the evaluated water quality parameters were appropriate for this production stage. Fertilization with molasses and dextrose efficiently controlled ammonia levels and ammonia did not reach the average concentrations that are considered toxic for the species (total ammonia < 1.3 mg L −1 and free ammonia < 0.05 mg L −1 ). The number of heterotrophic bacteria in the water was greater in the molasses and dextrose groups than in the control group. However, there was no difference in Vibrionaceae count between groups. There was no difference between groups in survival (>85%), length (6.15 mm), dry weight (0.17 mg) of postlarvae 5. Treatment with dextrose or molasses required approximately 12% of the water used by the control group. L. vannamei production rates and water quality were maintained without water exchange using a biofloc system supplemented with dextrose or molasses. [ABSTRACT FROM AUTHOR]

Malgré un marché potentiel important, peu d'études ont examiné les possibilités de développement de l'élevage intensif de la perche (Perca fluviatilis) en bassins ou en cages. L'objectif de cette étude initiale était d'évaluer l'effet de la température et du tri en fonction du poids corporel sur la croissance de perches élevées en conditions intensives. Les essais ont été réalisés avec des alevins de perche sevrés (1,9 g) sur une alimentation artificielle, placés en bassins alimentés par de l'eau du système de refroidissement d'une centrale nucléaire. La croissance est légèrement supérieure (+ 14,5 %) à une température de 26,5 °C par rapport à celle enregistrée à 22,9 °C. Cette différence est non significative (p>0,05), probablement parce que ces 2 températures se situent dans la gamme des températures optimales pour la croissance de la perche. Une infestation (taux de contamination : 24,5 %) par le cilié Heteropolaria sp est apparue à une température de 26,5 °C. Les perches, triées et séparées en 3 groupes distincts en fonction du poids corporel au début de l'expérience, ont présenté, après 234 jours d'élevage, une augmentation du polymorphisme de la croissance dans chaque groupe se traduisant par une superposition partielle des distributions des poids corporels. Une analyse de covariance indique que les 3 groupes ont présenté des vitesses de croissance comparables (F = 1,2). En élevage intensif, il apparaît que la perche présente une grande variabilité de croissance, ce qui renforce la nécessité de trier fréquemment les poissons.

During the management practices in fish farming, the use of anesthetic drugs can configure a security to the producer, as these products have the ability to reduce the metabolism of animals. The present study aimed to find the best dose of benzocaine, eugenol for anesthesia induction, recovery in 'mandi-pintado' juvenile. One hundred, four fish with an average weight of 55.6 ± 15.3 g, mean total length 18.4 ± 1.4 cm were used. The study was conducted in a completely randomized design with 13 treatments, i.e. seven different concentrations of eugenol (40, 70, 100, 130, 160, 190, 220 mg L-1), six concentrations of benzocaine (125, 150, 175, 200, 225, 250 mg L-1), where for each treatment eight randomly chosen fish (n = 8) were used, exposed individually for each concentration. Eugenol for anesthesia was effective in 'mandi-pintado' in different doses. However, benzocaine concentration of 125 mg L-1 was not efficient. Under the experimental conditions, the best concentration of eugenol for anesthesia induction, recovery in 'mandi-pintado' was 70 mg L-1, of benzocaine was 200 mg L-1. [ABSTRACT FROM AUTHOR]