Search Results (72)

The rising scarcity and cost of fishmeal due to overfishing and environmental challenges demand alternatives. Black soldier fly (Hermetia illucens) larvae (BSFL) meal, with its nutritional value, shows promise as a sustainable supplement for aquaculture species. This study evaluated the effects of BSFL meal supplementation on growth performance, survival, feed conversion efficiency, and meat quality in juvenile swamp eels (Monopterus albus) initially weighing 4.0 ± 0.5 g. The eels were fed diets with 0% (control), 10%, 30%, and 50% BSFL meal for three months. Growth performance was assessed using the absolute growth rate (AGR) and the specific growth rate (SGR). Feed conversion ratios (FCRs), survival rates, and meat quality metrics, including fillet percentage, crude protein, and moisture content, were analyzed. Statistical differences among groups were evaluated using one-way ANOVA followed by Tukey’s post hoc test for pairwise comparisons. The 30% BSFL group exhibited superior performance, achieving the highest AGR and SGR (p < 0.05) and the lowest FCR (2.33 ± 0.03). Fillet percentage was highest in this group (27.3% ± 0.7%), with no significant differences in crude protein or moisture content. Survival rates were consistent across treatments (75.2–76.0%, p > 0.05). These results confirm that 30% BSFL supplementation optimally enhances productivity and meat quality in swamp eels, highlighting BSFL meal’s potential as a sustainable aquafeed alternative. Full article

The expansion of aquaculture necessitates innovative disease detection methods to ensure sustainable production. Fish diseases caused by bacteria, viruses, fungi, and parasites result in significant economic losses and threaten food security. Traditional detection methods are labor-intensive and time-consuming, emphasizing the need for automated approaches. This study investigates the application of convolutional neural networks (CNNs) for classifying freshwater fish diseases. Such CNNs offer an efficient and automated solution for fish disease detection, reducing the burden on aquatic health experts and enabling timely interventions to mitigate economic losses. A dataset of 2444 images was used across seven classes—bacterial red disease, bacterial Aeromoniasis disease, bacterial gill disease, fungal disease, parasitic diseases, white tail disease, and healthy fish. The CNNs model incorporates convolutional layers for feature extraction, max-pooling for down-sampling, dense layers for classification, and dropout for regularization. Categorical cross-entropy loss and the Adam optimizer were used over 50 epochs, with continuous training and validation performance monitoring. The results indicated that the model achieved an accuracy of 99.71% and a test loss of 0.0119. This study highlights the transformative potential of artificial intelligence in aquaculture for enhancing food security. Full article

The covert mortality nodavirus (CMNV), an emerging pathogen that infects several species severely in aquaculture, including marine shrimps, freshwater prawns, and crabs, has been detected in both wild Artemia and commercial Artemia cysts. Utilization of Artemia from unknown sources can impose considerable biosecurity risks in hatchery operations; therefore, effective hatching methods to eliminate the pathogenic potential from CMNV-positive (CMNV+) Artemia cysts are urgently needed. In this work, we assessed the efficacy of three treatment methods of disinfecting CMNV+ Artemia cysts during hatching: (1) decapsulation of Artemia cysts with Na₂CO₃ (sodium carbonate) and NaClO (sodium hypochlorite) at various durations before hatching; (2) application of different concentrations of formalin in hatching water; (3) combinations of decapsulating Artemia cysts and formalin-treated hatching water. Hatching CMNV+ Artemia with disinfected seawater only served as the control. The virus located on the cyst shells attached/infected Artemia larvae during hatching and remained active for a prolonged time of 7 days. The viral load of empty shells decreased with the decapsulation treatment time. After a 45 min treatment of decapsulation, CMNV on shells, as well as larvae, were eliminated successfully. Furthermore, decapsulation shortened the hatching time of the cysts from 19 h to 12 h. Ten ppm formalin in the hatching water could block the transmission of CMNV from the shells to the newly hatched larvae, although at this level it was insufficient to eliminate the virus from the shells completely. While use of 30 ppm formalin or higher dosage could eliminate CMNV, however, it also reduced the hatching rates of the Artemia cysts. A combination of decapsulation (treated with Na₂CO₃-NaClO for 15 min) and 10 ppm formalin in hatching water effectively eliminated the CMNV. This study developed a practical, effective, and reliable treatment method for hatching Artemia to ensure biosecurity in aquaculture hatcheries. Full article

High evaporation rates due to solar intensity and low precipitation could represent a challenging culture environment in northwestern Mexico, generating osmotic stress in shrimp due to high salinity. Bacterial infections by pathogenic Vibrio strains are highly virulent in shrimp culture. This study evaluated betaine aldehyde dehydrogenase (BADH) activity and glycine betaine (GB) levels in Litopenaeus vannamei under high salinity levels plus experimental infection with virulent Vibrio parahaemolyticus. At 35 ppt (control group) and 40 ppt after infection, GB levels increased two-fold in the gills except at 45 ppt and were significantly higher at 50 ppt. The highest GB levels were in the hepatopancreas of the uninfected group at 45 ppt. In the gills, BADH activity decreased after 2 h of exposure at 40 and 45 ppt; at 50 ppt, there was a significant increase in the uninfected groups. However, upon infection, activity increased at all salinities except 50 ppt. In the hepatopancreas of the uninfected groups, the highest activity was at 40 ppt and this was lowest at 50 ppt after 8 h. In the muscles, BADH was detectable at all salinities; infection caused an increase in its activity at 45 and 50 ppt. Despite sudden exposure to high salinity plus experimental infection, our results show that Litopenaeus vannamei does not inhibit BADH activity, allowing GB synthesis, which may play a role in shrimp survival under these conditions. Full article

Disinfection of fish eggs with iodophor is a common biosecurity procedure. This study evaluated the effects of three concentrations of iodine on walleye (Sander vitreus) egg survival and bacterial loadings. Approximately five hours post fertilization, eggs from ten female walleyes were disinfected in active iodine concentrations of 0, 100, 200, and 400 mg/L for 10 min. There was a significant decrease in survival in the 200 mg/L treatment group compared to the 0 mg/L (control) and 100 mg/L groups. Near-total mortality occurred in the eggs receiving the 400 mg/L disinfection regime. Bacterial Colony Forming Units (CFU) were significantly reduced with any iodine disinfection compared to the control, but there was no significant difference in CFU among any of the iodine treatment concentrations. There was no relationship between egg survival and either pre- or post-disinfection CFU levels. These results indicate that 10 min treatments of active iodine at a concentration of 100 mg/L can be safely used to reduce bacterial loadings on newly spawned walleye eggs, but complete disinfection will not occur. Higher iodine concentrations, which lead to walleye egg mortality, do not further decrease bacterial numbers. Full article

Comparable and reproducible research is needed to improve Pacific white shrimp (PWS) aquaculture. These experiments typically involve before-and-after measurements of the same individual for paired statistical testing. However, marking shrimp with external or internal tags is challenging, especially for juveniles. A possible alternative is to rear shrimp individually in single-shrimp systems. While such systems may also prevent competitive interactions, PWS are considered social animals and individual rearing may negatively affect social behavior. Therefore, the general goal of this study was to evaluate the effects of single-shrimp versus multi-shrimp systems on the survival, growth, and welfare of juvenile PWS using a randomized controlled trial with group sizes of one, three, and five individuals. We found that shrimp kept individually had a higher survival rate, higher final body weights and lengths, and longer antennae than shrimp kept in groups of three or five. The incidence of eye cataracts was not significantly different among groups. Based on these results, we conclude that the individual rearing of juvenile PWS has no negative effects on survival, growth, or welfare. Therefore, a single-shrimp system could be an alternative to individually marked shrimp to allow paired statistical testing in experimental trials, especially when using post-larvae or juvenile specimens. Full article

The tambaqui (Colossoma macropomum) is Brazil’s most farmed native species, playing a crucial role in aquaculture. This study aimed to evaluate growth, hematological, biochemical, and body condition (Kn) parameters of tambaqui under two stocking densities in a recirculating aquaculture system (RAS). A total of 240 tambaqui (12.2 ± 4.1 g; 6.63 ± 0.73 cm) were distributed across six experimental units in two treatments (SD1 = 140 fish m⁻³; SD2 = 180 fish m⁻³) with three replicates. After 45 days, no significant differences were observed in water quality or zootechnical performance (p > 0.05), with final productivities of 8.64 ± 1.85 kg m³ and 9.46 ± 1.95 kg m³ for SD1 and SD2, respectively. Elevated plasma glucose, cholesterol, and triglyceride levels indicated energy reserve mobilization, suggesting some physiological response to higher stocking densities. However, other hematological and body condition parameters, including condition factor (Kn), indicated no significant adverse effects. These findings suggest that tambaqui can tolerate these stocking densities in RAS without compromising body condition, supporting the species’ intensive farming potential in controlled systems. This study highlights the importance of balancing productivity and physiological conditions in aquaculture management. Full article

This review evaluates regenerative aquaculture (RA) technologies and practices as viable pathways to foster resilient, ecologically restorative aquaculture systems. The key RA technologies examined include modern periphyton technology (PPT), biofloc technology (BFT), integrated multitrophic aquaculture (IMTA), and alternative feed sources like microalgae and insect-based diets. PPT and BFT leverage microbial pathways to enhance water quality, nutrient cycling, and fish growth while reducing environmental pollutants and reliance on conventional feed. IMTA integrates species from various trophic levels, such as seaweeds and bivalves, to recycle waste and improve ecosystem health, contributing to nutrient balance and reducing environmental impact. Microalgae and insect-based feeds present sustainable alternatives to fishmeal, promoting circular resource use and alleviating pressure on wild fish stocks. Beyond these technologies, RA emphasizes sustainable practices to maintain fish health without antibiotics or hormones. Improved disease monitoring programs, avoidance of unprocessed animal by-products, and the use of generally recognized as safe (GRAS) substances, such as essential oils, are highlighted for their role in disease prevention and immune support. Probiotics are also discussed as beneficial microbial supplements that enhance fish health by promoting gut microbiota balance and inhibiting harmful pathogens. This review, therefore, marks an important and essential step in examining the interconnectedness between technology, agroecology, and sustainable aquaculture. This review was based on an extensive search of scientific databases to retrieve relevant literature. Full article

Singapore’s aquaculture sector is critical to achieving the nation’s ‘30 by 30’ food security goal, which aims to produce 30% of its nutritional needs locally by 2030. However, the sector faces several significant challenges. Limited land and water resources, high operational costs, disease outbreaks, reliance on imported seedstock, and environmental impact are among the key issues. Additionally, the industry struggles with a shortage of skilled manpower and high dependency on foreign labour. This study explores these challenges in detail and suggests potential solutions to enhance the sustainability and productivity of Singapore’s aquaculture. Innovative farming techniques such as recirculating aquaculture systems (RASs) and vertical farming, advanced water quality management, and the adoption of renewable energy sources are recommended to address space and cost constraints. Developing local breeding facilities, enhancing education and training programs, and adopting sustainable practices are also crucial. The establishment of a national hatchery and increased investment in research and development (R&D) are essential for long-term growth. By implementing these strategies, Singapore can overcome the challenges in its aquaculture sector and ensure a sustainable future for local food production. Full article

The rapid growth of pangasius and tilapia aquaculture has created export opportunities for Bangladesh; however, this industry is facing multiple barriers to becoming a competitive whitefish exporter in the international market. We analyzed a widely used conceptual framework and reviewed the available literature to unpack the barriers to pangasius and tilapia exports in mainstream global markets. Primary data were collected by interviewing 60 associated stakeholders to consolidate the research objectives. A meta-analysis of the literature and primary data revealed that pangasius and tilapia exporters face various internal (company and product barriers) and external (industry, market, and macroenvironment barriers) barriers. To overcome these barriers, the pangasius and tilapia industries need separate export-oriented policies and legislation to be developed by the competent authority, namely, the Department of Fisheries (DoF), which needs to provide common guidelines to meet international standards of aquaculture practices, food safety, quality, certification, and export markets. The DoF should ensure robust oversight through effective monitoring and surveillance mechanisms to implement the regulations and policies. Drawing insights from China and Vietnam’s experiences in responsible aquaculture practices, navigating export markets, and instituting aquaculture certification could provide invaluable lessons for Bangladesh. Using these lessons to overcome impediments could catalyze the flourishing of Bangladesh’s pangasius and tilapia sectors in the global whitefish market. Full article

Preliminary evidence has showed an emergent serotype O3 (SO3) strain of Vibrio anguillarum to cause mortality in pre-smolt Atlantic salmon (Salmo salar) by injection with >10⁵ colony forming units (cfus). Here, we sought to identify the susceptibility of Atlantic salmon post-smolts to this emergent strain by both injection and cohabitation to better understand transmission risk within cultured salmon and possibly between salmon and Atlantic menhaden (Brevoortia tyrannus), where this strain was identified. We identified that although mortality could be induced with a high-dose (>10⁶ cfus) intraperitoneal injection of the emergent SO3 strain (cumulative mortality of 40%), post-smolt Atlantic salmon were highly refractory to a low dose (<10⁶ cfus; cumulative mortality of 3%) or cohabitation exposure (no mortality). A qPCR assay targeting this strain was developed and analytically validated, revealing the limited presence of bacterial DNA in the spleen of low-dose-injected fish (2/36) and no detections in sampled cohabitants (0/70) across three timepoints during the 27-day challenge. These results suggest that although Atlantic salmon can succumb to high-dose artificial infections with V. anguillarum SO3, the risk of natural transmissibility and susceptibility of Atlantic salmon to this emergent strain is anticipated to be low. Full article

European sea bass (Dicentrarchus labrax) is one of the most significant species farmed in the Mediterranean, yet a very perishable product. Its quality deteriorates rapidly as a result of three mechanisms: microbial activity, chemical oxidation, and enzymatic degradation. Microbial spoilage is the mechanism that contributes most to the quality deterioration of fresh and non-processed fish. To this end, our study aims to identify for the first time the combined effect of aquatic environment and harvest method on the composition and trajectory at storage at 0 °C of the European sea bass skin microbiome. Sampling was performed in two commercial fish farms in Western (WG) and Central Greece (CG) where fish were harvested using different methods: direct immersion in ice water or a mixture of slurry ice; application of electro-stunning prior to immersion in ice water. Samples were collected on harvest day and one week post-harvest. To profile the bacterial communities in the fish skin, 16S ribosomal RNA gene sequencing was used. The results and the following analyses indicated that the aquatic environment shaped the original composition of the skin microbiome, with 815 ASVs identified in the WG farm as opposed to 362 ASVs in the CG farm. Moreover, Pseudomonas and Pseudoalteromonas dominated the skin microbiome in the WG farm, unlike the CG farm where Shewanella and Psychrobacter were the dominant genera. All these genera contain species such as Shewanella putrefaciens, Pseudomonas aeruginosa, Pseudoalteromonas spp., and Psychrobacter sp., all of which have been implicated in the deterioration and spoilage of the final product. The different harvest methods drove variations in the microbiome already shaped by the aquatic environment, with electro-stunning favoring more diversity in the skin microbiome. The aquatic environment in combination with the harvest method appeared to determine the skin microbiome trajectory at storage at 0 °C. Although Shewanella had dominated the skin microbiome in all samples one week post-harvest, the diversity and the relative abundance of genera were strongly influenced by the aquatic environment and the harvest method. This study sheds light on the hierarchy of the factors shaping the fish skin microbiome and their importance for controlling post-harvest quality of fresh fish. Full article

A 60-day feeding experiment was conducted to examine whether (i) soybean meal (SBM) protein in the diet of Nile tilapia (Oreochromis niloticus) can be replaced with protein from spent brewer’s yeast (SBY); (ii) co-rearing with biofloc alters fish growth, feed conversion and protein efficiency compared with rearing in clear water; and (iii) accumulated protein quantity and quality in biofloc acts as a possible feed source for the fish in periods of low feed intake. The fish were reared in either a bio-recirculating aquaculture system (Bio-RAS) or a clear-water RAS (Cw-RAS). In Bio-RAS, the mechanical and biological filters used in Cw-RAS were replaced with an open bioreactor that delivered heterotrophic-based biofloc to the rearing tanks and also acted as a sedimentation trap for effluent water before recirculating it back into the rearing unit. The fish were fed four iso-nitrogenous and iso-energetic diets (~28% crude protein, ~19 MJ kg⁻¹ gross energy) in which SBM protein was replaced with increasing levels of SBY, with triplicate tanks per inclusion level. The results revealed that average fish growth was greater in a biofloc environment compared with clear water and also greater at higher inclusion levels of SBY. However, in both rearing environments, fish growth displayed a second-degree polynomial distribution with increasing SBY inclusion level, with a peak between 30% and 60% inclusion. Fish in the biofloc environment showed better feed conversion ratio and protein retention, likely through ingesting both given feed and biofloc. Biofloc contained a significant amount of accumulated protein with a high biological profile, thereby constituting a possible feed reserve for the fish. A conclusion underlined by the apparent improved feed conversion of Bio-RAS reared fish, where that ingestion of biofloc will reduce the need for external feed per unit growth. Full article

Coastal aquaculture and local fisheries interact in shared marine environments, influencing each other synergistically and/or antagonistically. Salmon farming, notably with open-net sea cages along the Norwegian coast, attracts wild fish due to increased food availability from uneaten feed, but it also exposes wild fish to farm emissions like waste and toxic chemicals (de-lice treatments, antifouling and medical agents). The attraction behaviour of wild fish can impact fatty acid composition in fish tissues, influenced by the high terrestrial fat content in salmon aquafeed. We study how the Atlantic cod, aggregating around salmon farms in a subarctic fjord in Northern Norway, can be affected, potentially altering their natural diet and fatty acid profiles. Our study compares the muscle-tissue fatty acid compositions of cod caught near aquaculture facilities (impact) versus fish caught in neighbouring fjords (control), and we hypothesise decreased omega-3 fatty acids near farms. The analysis revealed no significant differences in the fatty acid concentrations or categories between the impacted and control fish, challenging our initial expectations. However, differences were found for C18:1(n9)t (elaidic acid), with a higher value in the impacted fish. These findings suggest that salmon farming’s influence on cod’s fatty acid profiles in the flesh (i.e., relevant for the nutritional quality of the fillets that consumers eat) may be limited or minimal despite their aggregative behaviours around farms. The threshold levels of salmon feed consumed by wild cod before it affects the quality and survival of, e.g., sperm or other life stages, are not known and require new investigations. This study underscores the complexity of interactions between aquaculture and wild fisheries, impacting both ecological dynamics and consumer perspectives on seafood quality and health benefits. Full article

This study evaluates the effects of Christmas melon (Laganaria breviflorus)-based diets on the growth and hematology of African catfish (Clarias gariepinus) after a 6 (six)-month feeding trial. A total of 240 C. gariepinus juveniles with an average weight of 10.68 g were procured from the Fisheries and Aquaculture Department Hatchery Unit for the feeding trial. After acclimating for a week (7 days) using 2.00 mm Coppens feed (45% CP) twice per day, the fish samples were randomly distributed into 12 tarpaulin tanks of 4 ft × 4 ft × 4 ft with a 200 L water holding capacity (four (4) different treatments presented in triplicate). Twenty (20) fish per tank were fed twice daily with the compounded feed with varying dietary inclusion levels of Christmas melon (0% (control), 5%, 10% and 15%). The weights and lengths of the sampled fish were measured biweekly to determine the growth performance, while hematological parameters, such as the packed cell volume, erythrocytes, hemoglobin, and leucocytes were determined midway through and at end of the feeding trial. The data collected were analyzed using ANOVA, and the results revealed the optimum growth and nutrient utilization and hematological and serum biochemical parameters of C. gariepinus in T3. The length–weight relationship results revealed that the fish exhibited an isometric growth pattern with B-values above 3 across the treatments. In conclusion, the results obtained in this study revealed that Christmas melon (L. breviflorus) could replace wheat offal by up to 10% in the diet of C. gariepinus without negative effects on the obtained optimal growth performance, hematological parameters, or serum biochemistry. Full article