Search Results (125)

Aeromonas hydrophila (A. hydrophila) is responsible for causing abdominal dropsy, swimming abnormalities, skin ulcerations, and pale gills in fish. Vaccination is an essential strategy for disease prevention in aquaculture. This study evaluated the efficacy of an oral vaccine against A. hydrophila in Ctenopharyngodon idella (C. idella). The vaccine was formulated as feed-based monovalent pellets, incorporating or spraying formalin-killed A. hydrophila on/into commercial feed with 30% crude protein. Mineral and fish oils were used as adjuvants at 10% of the feed. Prior to the trial, the experimental feed groups were subjected to quality and safety tests. Grass carp fingerlings (20 ± 5 g) were divided into seven groups (n = 20 per group): sprayed vaccinated feed with fish oil (SVFF), incorporated vaccinated feed with fish oil (IVFF), sprayed vaccinated feed with mineral oil (SVFM), incorporated vaccinated feed with mineral oil (IVFM), sprayed vaccinated feed (SVF), incorporated vaccinated feed (IVF), and a control group. Feed was provided at 3% of body weight for 60 days. Immunomodulation was investigated through lysozyme activity, antibody titers, and immunoglobulin M (IgM). The IVFF group showed significantly enhanced immunity and growth performance, with an 87% protection rate, 13% mortality, and the highest relative percentage survival (83%) following intraperitoneal A. hydrophila (6.8 × 10⁹ CFU/mL) challenge. Histological analysis indicated minimal pathological changes in the IVFF group compared to controls. Fish oil as an adjuvant enhanced immunity without adverse health effects. Overall, this study demonstrated that feed-based monovalent vaccines effectively improve immune responses and provide protection against A. hydrophila in C. idella. Full article

The aim of this study was to develop a mathematical model to predict the body weight of tilapia fingerlings using variables obtained through computer vision. A total of 2092 tilapia fingerlings and juveniles, weighing between 10 and 100 g, were fasted for 12 h, anesthetized, weighed, and photographed using an iPhone 12 Pro Max at 33 cm height in a closed container with different bottom colors. Images were segmented using Roboflow’s instance segmentation model, achieving 99.5% mean average precision, 99.9% precision, and 100% recall. From the segmented images, area, perimeter, major axis (MA), minor axis (SA), X and Y centroids, compactness, eccentricity, and the MA/SA ratio were extracted. Seventy percent of the data was used to build the model, and 30% for validation. Stepwise multiple regression (backward selection) was performed, using body weight as the dependent variable. The prediction model was: −17.7677 + 0.0007539(area) – 0.0848303 (MA) – 0.108338(SA) + 0.0034496(CX). The validation model showed similar coefficients and R² = 0.99. The second validation, using observed versus predicted values, also yielded an R² of 0.99 and a mean absolute error of 1.57 g. Correlation and principal component analyses revealed strong positive associations among body weight, area, axes, and predicted values. Computer vision proved effective for predicting tilapia fingerlings’ weight. Full article

Effective transport strategies are critical for the survival and welfare of juvenile Ictalurus punctatus, but the effects of pre-transport salt bath treatments remain uncertain. In this study, we systematically evaluated the effects of pre-transport salt bath acclimation at 0‰ (S1), 1‰ (S2), 5‰ (S3), and 9‰ (S4) salinity for 30 min on stress resilience and recovery in fingerlings during 12 h of simulated transport and 24 h of recovery. All fish survived, but total ammonia nitrogen (TAN) increased, and pH decreased in all groups, except S3, which showed significantly lower TAN and higher pH (p < 0.05). The S3 and S4 groups showed attenuated increases in serum cortisol and glucose, with S3 exhibiting the fastest return to baseline levels and stable serum sodium and potassium levels. Liver antioxidant enzyme activities in group S3 remained stable, with the lowest malondialdehyde (MDA) accumulation. Integrated biomarker response (IBR) and histological analyses demonstrated that S3 had the lowest systemic stress and tissue damage, whereas S1 and S4 displayed marked cellular disruption. These results indicate that a 5‰ salt bath applied prior to transport may improve water quality, mitigate stress responses, and preserve tissue integrity in juvenile channel catfish. Further studies are needed to confirm these findings in other species and under commercial transport conditions. Full article

Background: The relationship between genetic diversity and fitness is well understood, but few studies have investigated how behavior influences genetic diversity, or vice versa. We investigated the relationship between feeding behavior (on a pelleted diet) and genetic diversity in pikeperch, a piscivorous species. Methods: A total of 135 juvenile pikeperch from the same stock were grouped into three behavioral groups: pellet consuming, pellet refusing, and cannibalistic. Eighteen microsatellite markers were used to characterize the genetic diversity and structure of individuals. Results: The juveniles were classified into two genetic clusters: one dominated by pellet-consuming individuals and the other by pellet-refusing individuals containing equal proportions of cannibal individuals. Three of the microsatellite markers were under selection, but only one showed significant genetic segregation between the groups. For this marker, the pellet consumption was associated with low fragment length. Individual multilocus heterozygosity was significantly higher in the pellet-refusing group. Conclusions: These results suggest that pellet consumption acts as an uncontrolled selective force during domestication, influencing the genetic variability of domesticated populations. The ability to habituate to pellets has a significant genetic basis. Cannibalism does not affect genetic variability, and the emergence of the trait is independent of the propensity to consume pellets. Full article

This study investigated the effects of feeding striped beakfish (Oplegnathus fasciatus) newly hatched larvae on the survival and growth of kawakawa (Euthynnus affinis) larvae and juveniles, as well as their relative growth patterns. Fertilized eggs of kawakawa were reared in 1 m³ experimental tanks until 13 days post-hatch (dph). From 3 to 8 dph, larvae were fed enriched rotifers, and from 9 to 12 dph, they were assigned to two experimental groups: one receiving only a formulated diet and the other receiving a combination of the formulated diet and 10,000 striped beakfish newly hatched larvae every day in each tank. The group fed newly hatched larvae exhibited approximately 36% greater growth than the group fed only the formulated diet. However, survival at 13 dph was approximately 34% lower, suggesting that further investigation is needed to determine the optimal feeding quantity of newly hatched larvae. The relative growth patterns of larvae and juveniles reared in a commercial 30 m³ tank showed morphological traits characteristic of scombrid fish, such as a longer preanal length and upper jaw length. Growth patterns varied at three key body lengths (notochord length or standard length; 3, 8–10, and 30 mm), as well as at their corresponding standard lengths. In kawakawa, the upper jaw exhibited early accelerated growth compared to other scombrid species. This characteristic is believed to facilitate the early onset of piscivory under captive conditions. Full article

This study aimed to evaluate the dynamics of total carbon (TC), total nitrogen (TN), total phosphorus (TP), and some indicators of environmental sustainability of Nile tilapia reared in a biofloc technology (BFT) system. Nile tilapia fingerlings were cultured in three BFT units of production (4.2 m³ each) at a stocking density of 395 fish/m³. After 70 days, the survival rate was 98.05%, with a final average weight of 20.43 g, and apparent feed conversion of 1.05. Nutrient inputs were from supply water, initial fish biomass, and feed; outputs were measured from the final fish biomass and effluent. TC, TN, and TP concentrations in the water increased linearly over time (p < 0.001) by 1.54, 1.66, and 0.44 mg/L, respectively. Feed contributed over 88% of nutrient inputs, while fish final biomass accounted for over 50% of output. Nutrient retention in fish final biomass was 29.74% (TC), 45.38% (TN), and 46.34% (TP). The system had low eutrophication potential, estimated at 57.39 kg TC, 20.02 kg TN, and 5.70 kg TP per ton of fish. Water use was minimal (0.0074 m³/ton), but energy demand was high (114.59 MJ/kg). The closed system reduces biodiversity risks by preventing fish escape. In conclusion, BFT supports high fish productivity with efficient nutrient use, minimal water use, and limited environmental impact, contributing to environmentally sustainable aquaculture. Full article

To meet the growing demand for sustainable aquaculture, the biofloc technology (BFT) system has emerged as a promising solution, offering high productivity, improved water use efficiency, and enhanced environmental and biosecurity performance. Economic and risk analyses are essential tools for identifying the key technical and economic factors that determine the profitability and long-term sustainability of aquaculture systems. This study aimed to evaluate the economic feasibility and the risk associated with Nile tilapia juvenile production in a BFT system. Economic viability indicators were calculated using real data on capital investment, operational costs, and zootechnical performance from a production cycle. Scenario analyses were conducted to assess the effects of fluctuations in input prices and survival rates on overall economic outcomes. Stochastic simulations were also conducted to determine the probabilities of economic results. The items with the greatest impact on costs were the acquisition of the greenhouse and fingerlings, representing 27.64% of the initial investment and 33.24% of the operating cost, respectively. The BFT system showed a positive net margin and profitability per production cycle, with the exception of the pessimistic scenario. The risk analysis demonstrated that in 87.29% of the simulations resulted in a positive profit. Thus, the production of tilapia juveniles in a BFT system is an economically viable investment. However, its success is contingent upon specific technical and market conditions, underscoring the need for careful management and context-specific planning. Full article

Anesthesia is commonly used in sturgeon aquaculture to reduce stress and pain during handling and procedures. This study compared the effects of clove oil (rich in eugenol) and propofol—an anesthetic widely used in human and veterinary medicine—on Persian sturgeon (Acipenser persicus) fingerlings. A total of 405 fish (6.88 ± 0.90 g) were exposed to varying concentrations of clove oil (25, 50, 75, 100 mg L⁻¹), propofol (10.0, 12.5, 25.0, 50 mg L⁻¹), or no anesthetic (control) in triplicate. Hematocrit and monocyte levels remained unchanged across treatments, but the highest doses of both anesthetics significantly reduced leukocyte percentages (p = 0.049 and p = 0.043, respectively). While serum enzymes were stable, cortisol levels increased significantly at the highest concentrations of both clove oil (38.92 ± 5.1 ng mL⁻¹; p = 0.001) and propofol (36.48 ± 3.4 ng mL⁻¹; p = 0.035), indicating secondary stress responses. Propofol at 25 mg L⁻¹ showed fast induction and recovery times and induced milder stress compared to clove oil. Overall, short-term anesthesia with both agents triggered physiological stress, but propofol at 25 mg L⁻¹ appeared more suitable for minimizing adverse effects in Persian sturgeon fingerlings. Full article

Yellow perch (Perca flavescens), a native species of the Great Lakes, has experienced a significant decline in wild harvest since the 1990s, leading to an increased reliance on aquaculture. This study aimed to optimize feeding rate for yellow perch by evaluating the effects of various feeding rates (1.5%, 3.0%, 4.5%, 6.0%, and 7.5% body weight (BW)/day) on growth, nutrient retention, and heat shock protein 70 expression in perch fingerlings (initial BW: 1.73 ± 0.11 g) over a four-week period. Following the feeding trial, an acute heat shock was induced by raising the water temperature from 23 °C to 31 °C, followed by an 18 h recovery period. Results indicated that both growth rate and whole fish lipid content increased with higher feeding rates (p < 0.05), while nutrient retention decreased. Growth and energy retention did not significantly improve beyond 4.5%, with maximum energy retention observed at 3.9% BW/day. Heat shock protein 70 expression was highest in liver tissue at a feeding rate of 6.2% BW/day, indicating that higher feeding levels may enhance thermal stress response. These results indicate that a feeding rate of 4.5% BW/day supports optimal growth, while 6.2% BW/day may be necessary to improve heat shock tolerance. The study provides practical insights for refining feeding strategies in yellow perch aquaculture. Full article

This study evaluated the impact of Bacillus subtilis supplementation on growth, antioxidant status, digestive enzyme activities, hematological parameters, blood biochemistry, and immune responses in Nile tilapia (Oreochromis niloticus) fingerlings. A total of 180 fingerlings (mean weight: 5 ± 0.5 g) were randomly assigned to four groups: a control group and three probiotic-supplemented groups with 10⁶ (S-1), 10⁸ (S-2), and 10¹⁰ (S-3) CFU g⁻¹ of B. subtilis, following a completely randomized design. Fish were fed twice daily for eight weeks. Results showed that the 10¹⁰ CFU g⁻¹ group exhibited significantly higher weight gain (43 g), specific growth rate (2.5%/day), and better feed conversion ratio (0.7) compared to the control (30 g, 2.2%/day, and 1.4, respectively). Hematological parameters (WBC, RBC, hemoglobin) and immune responses (phagocytic activity, lysozyme) were significantly improved. Blood biochemistry showed decreased ALT/AST levels and increased ALP activity. Digestive enzymes (protease, lipase, amylase) and antioxidant activity (GPx, CAT, SOD) were enhanced, with reduced MDA levels. No significant differences were observed in survival rates or stress responses. These findings suggest that B. subtilis supplementation at 10¹⁰ CFU g⁻¹ improves growth, immune function, and antioxidant status, making it a promising probiotic for Nile tilapia. Full article

Edwardsiella piscicida septicemia is a significant threat to aquaculture, causing substantial production and economic losses. The causative bacterium E. piscicida infects multiple fish species of aquaculture relevance. This study investigated the pathogenicity of catfish-derived E. piscicida in largemouth bass (Micropterus salmoides) fingerlings. The experimental infection of largemouth bass using genotypically distinct E. piscicida isolates resulted in significant fish mortality independent of the isolate genotypes. A specific correlation between discrete E. piscicida genotypes and fish mortalities was not identified. The histopathological assessment of tissues from infected fish revealed inflammatory lesions characteristic of bacterial septicemia. This study provides insights into the pathogenesis of heterologous E. piscicida isolates in largemouth bass fingerlings, which could be crucial in developing effective pathogen-targeted management strategies to combat a deadly disease. Full article

A feeding trial was conducted for 120 days in a pilot field condition to evaluate ginger powder (GP; Zingiber officinale) as a feed supplement for Labeo rohita to improve immunity, blood metabolic profile, and resistance to Aeromonas hydrophila bacterial infection. The study was conducted following a complete randomized design in outdoor cemented tanks (20 m²) with a stocking density of 30 fish (average weight: 20.5 g) per tank. L. rohita fingerlings were divided into five groups and fed a diet with no GP supplementation (control diet; C) or a diet supplemented with 5 g (GP5), 10 g (GP10), 15 g (GP15), or 20 g (GP20) of GP per kg of the control diet. The results showed that fish well-being, determined by measuring the condition factor, remained higher than 1.0 for all the experimental groups. The condition factors of all the groups were not significantly different between the groups, suggesting GP had no negative impact on overall fish health. Immune responses significantly improved in the groups fed with diets supplemented with GP at doses of 10 to 15 g per kg of their diet, as seen in respiratory burst activity, total immunoglobulins, and lysozyme activity at 60 and 120 days. Blood metabolic variables, particularly the albumin level, tended to show some level of improvement in the GP15-fed group. However, the effect was not significant. Total protein and globulin levels and the albumin/globulin ratio were not significantly affected by dietary GP. Importantly, fish fed the GP15 diet showed the highest resistance to the A. hydrophila challenge. In conclusion, ginger powder holds promise as a health-promoting nutraceutical for farmed L. rohita, contributing to their sustainable farming. Full article

Spodoptera frugiperda (Lepidoptera: Noctuidae) and Tenebrio molitor (Coleoptera: Tenebrionidae) are two prominent pests of maize and its stored grains, respectively. Botanical pesticides have been proposed as an alternative for their management. This study evaluated the insecticidal activity of Salvia connivens (Lamiaceae) methanolic extract and rosmarinic acid against S. frugiperda and T. molitor by adding them to an artificial diet, as well as their ecotoxicological effects on Poecilia reticulata (Cyprinodontiformes: Poeciliidae) and Danio rerio (Cypriniformes: Danionidae) through acute toxicity tests. The methanolic extract showed higher mortality activity against S. frugiperda (LC₅₀ = 874.28 ppm) than against T. molitor (LC₅₀ = 1856.94 ppm) and was non-toxic to fish. Rosmarinic acid, the most abundant compound in the extract (80.45 mg g⁻¹), showed higher activity against S. frugiperda (LC₅₀ = 176.81 ppm). This compound did not cause a toxic effect on adult P. reticulata at the tested concentrations. However, in P. reticulata fingerlings and D. rerio adults, it was non-toxic, except in D. rerio embryos, where it was slightly toxic. These findings suggest that S. connivens methanolic extract has potential as a botanical product for the management of S. frugiperda and T. molitor with low ecotoxicological impact, while rosmarinic acid may be a useful compound for the management of S. frugiperda. Full article

The present investigation attempts to evaluate the impact of the dietary inclusion of chia (Salvia hispanica) seed oil (CSO) on the indices of haemato-immunology, metabolic enzymes, and expression of immune-responsive cytokine genes in Labeo rohita (rohu) fingerlings. The responses were observed in a 60-day feeding trial, set up with a total of 180 rohu fingerlings (19.74 ± 0.33 g) randomly allocated to four treatment groups with three replicates each. The groups were fed with a basal diet incorporated with 0%, 1.0%, 2.0%, and 3.0% CSO, denoted as control, CSO (1), CSO (2), and CSO (3), respectively. Significant (p < 0.05) augmentation of hematological indices such as total protein and globulin levels was observed in the group fed a 1.0% CSO-supplemented diet. Serum glucose, cholesterol, triglycerides, and complement reactive protein levels declined, whereas marker anti-oxidative enzymes (SOD, CAT, and GST) and protein metabolic enzymes (ALT and AST) increased (p < 0.05) in the lowest CSO-supplemented group. A significant upregulation of inflammatory cytokine viz. IL-1β, IFN-γ, TNF-α, and TLR22 alongside downregulation of IL-10 was noted in various tissues. The results support the inclusion of 1.0% CSO as a prospective dietary vegan substitute to fish oil in rohu aquaculture. Full article

Small indigenous fish (SIF) production from wetlands provides nutritious food and supports the livelihood of the fishing community. The present study investigated the fish production trend, SIF diversity, and role of environmental and climatic parameters in Beledanga, a floodplain wetland in lower Ganges, through the sampling and collection of data from the local fishermen cooperative society. The fish catch composition in the wetland shifted after 2019, with the increased Ctenopharyngodon idella (grass carp) contribution from 11% to 17% due to the introduction of in situ seed-raising technology of an HDPE (high-density polyethylene) pen culture system. The fish fingerling stocking has a profound impact on fish production (R² = 0.60, p = 0.007). During the study period, 19 species of SIF were recorded, with a higher abundance observed in the monsoon season. The naturally occurring SIF contributed 16% of the total fish catch, with the highest catch in 2011 (11,970 kg). Water pH and phosphate content are the two most important environmental parameters that influence SIF. The generalized additive model (GAM) indicated that the optimum annual rainfall for fish production in the wetland was between 750 and 1250 mm. The average annual fish production of 43,017 kg through stocking and SIF support the livelihood and nutritional security of the fishers. As the SIF showed a decreasing trend of production, habitat protection, scientific stocking, and in situ enclosure culture are recommended for sustainable enhancement of fish production and to conserve the SIF diversity. Full article