Abstract This study aimed to evaluate the interactive effects of rearing densities and supra‐nutritional levels of vitamin E on fish performance. Triploid rainbow trout juveniles (40.44 ± 1.27 g) were distributed into 18 tanks at medium (MD, 30 kg/m3, 45 fish/tank) and high (HD, 60 kg/m3, 90 fish/tank) densities. The trial was designed with two fish rearing densities (MD and HD), each fed 0, 200, or 400 mg/kg vitamin E‐supplemented diets (actual contents of 104.7, 303.5, and 496.8 mg/kg, respectively), a 2 × 3 factorial design. After 63 days, the final weight, body weight increase, SGR, FCR, and PER were significantly affected by both rearing density and vitamin E main effects (p < 0.05). Additionally, significant density × vitamin E interactions were observed for the final weight, FCR, and PER (p < 0.05), with HD400 fish performing comparable with MD groups. Serum cortisol levels were significantly lower in all MD groups and HD400 fish than in the other groups, whereas an inverse pattern was observed for serum osmolality (p < 0.05). Serum lysozyme activity and total Ig and globulin contents in MD groups were significantly higher than in HD groups (density effect, p < 0.001), and supra‐nutritional vitamin E supplementation significantly increased these parameters (vitamin E effect, p < 0.05). Serum alternative complement (ACH50) and liver glutathione peroxidase (GPx) activities in the MD and HD400 groups were significantly higher than in HD200, and the lowest in the HD0 group (p < 0.05). Liver superoxide dismutase (SOD) activity was lowest in the HD0 group. Liver malondialdehyde content was significantly lower in MD200, MD400, and HD400 than in other groups (p < 0.05). Among the tested levels, 400 mg/kg vitamin E supplementation ameliorated the negative impacts of high rearing density (60 kg/m3) on triploid rainbow trout juveniles by improving growth, innate immunity, antioxidant capacity, and tolerance to high‐density stress.
Abstract Aquaculture in Kenya is rapidly expanding and has become an important subsector for promoting food security, employment creation, and economic diversification, as capture fisheries continue to decline amid rising demand for fish. This review examines the socioeconomic and policy implications of genetic improvement of farmed fish species in Kenya in the context of sustainable aquaculture development. We synthesize evidence on genetic improvement approaches, including selective breeding, triploidy, marker‐assisted selection, and emerging gene‐editing technologies, and assess their contributions to enhanced aquaculture productivity and the conservation of aquatic genetic resources. Selective breeding programs in Asia and Africa have reported growth improvements of 30%–85%, improved feed efficiency, and higher survival rates, highlighting the potential of genetic improvement to enhance fish production and farmer livelihoods in Kenya. The review highlights existing national strategies, guidelines, and institutional frameworks for genetic improvement while identifying key challenges related to hatchery certification, genetic erosion, biosecurity risks, and weak institutional coordination. Drawing on international best‐practice frameworks and comparative experiences from Asia, the article evaluates gaps in Kenya's current policy and institutional landscape, including the Fisheries Management and Development Act 2016 and the Draft National Aquaculture Policy 2025. We argue that realizing the full socioeconomic benefits of genetic improvement depends on the establishment of a coordinated national breeding and broodstock management program, strengthened research and extension capacity, and harmonized governance across national and county levels to support a sustainable and competitive aquaculture sector.
Abstract Fish vaccination has been practiced globally for several decades and is increasingly recognized as a cornerstone of sustainable disease management in aquaculture, offering an effective alternative to antibiotic and chemotherapeutic use. This PRISMA‐ScR guided Scoping Review synthesized evidence from 173 peer‐reviewed studies and reports to evaluate vaccine platform efficacy, administration routes, adoption challenges, and emerging directions. The major findings indicate that across laboratory and field trials, multivalent injectable vaccines in salmonids consistently achieved Relative Percent Survival (RPS) values exceeding 80% against bacterial pathogens such as Aeromonas salmonicida and Vibrio anguillarum, contributing to a documented 99% reduction in antibiotic use in European countries' aquaculture sector. Experimental immersion and oral vaccines for warm‐water species such as tilapia and carp demonstrated more variable efficacy, with RPS typically ranging from 50% to 75%, reflecting challenges in antigen delivery and uptake. Economic analyses from industrial salmon and tilapia farming report positive Benefit–Cost Ratios (BCR) ranging from 2.5:1 to 5:1, driven by reduced mortality and improved feed conversion ratio (FCR). However, for small‐ and medium‐scale fish farms in low‐ and middle‐income countries (LMICs), vaccine adoption remains below 15% due to high upfront costs, cold‐chain limitations, and lack of locally validated formulations. Critical knowledge gaps persist, including insufficient field validation of vaccine efficacy under commercial conditions, the absence of harmonized immune assays to enable cross‐study comparisons, and limited understanding of environmental modifiers such as temperature, oxygen, and stress on vaccine performance. Future research should prioritize integrating epidemiological modeling for disease prioritization and developing affordable, thermostable vaccines tailored to LMIC fish species. Addressing these gaps through targeted investment and partnerships will enhance aquaculture resilience, reduce antibiotic dependency, and strengthen global food security.
Abstract Opportunistic pathogens represent a significant threat to shrimp aquaculture, as they can reduce productivity and cause substantial economic losses. Plant‐derived compounds have been investigated as potential alternatives for controlling bacterial infections associated with shrimp farming. In this study, a bioprospecting screening of 31 plant species collected from the localities of Taura and Sangolquí (Ecuador) was conducted to evaluate their antioxidant and antibacterial activities against bacterial species associated with aquaculture systems. Among the evaluated extracts, Eucalyptus globulus Labill. and Psidium guajava L. leaves exhibited notable bioactive potential and were selected for further analysis. The antioxidant activity of the extracts was assessed using ferric reducing antioxidant power (FRAP) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assays. Antibacterial activity was evaluated using disk diffusion and microdilution methods. In addition, fractions from the most active extracts were analyzed using HPLC‐DAD‐MS/MS to explore their chemical composition and potential association with antibiofilm activity. The results showed that Eucalyptus globulus and Psidium guajava leaf extracts exhibited minimum inhibitory concentration (MIC) values ranging from 250 to 20,000 μg/mL against the tested Vibrio species and P. aeruginosa strains, with Eucalyptus extracts generally showing lower MIC values and a more consistent inhibitory profile across extraction solvents. Antioxidant activity was also observed in methanolic extracts. Fraction F5 of the Eucalyptus leaf extract reduced biofilm biomass by up to 76.09% and viable cells by 70.15%. For Psidium guajava leaves, fractions F1 (61.98%–71.69%), F4 (55.14%–70.02%), and F6 (38.84%–65.88%) showed the highest antibiofilm activity, particularly against mature biofilms associated with Vibrio spp., while limited activity was observed against Pseudomonas aeruginosa. HPLC‐DAD‐MS/MS analysis tentatively identified several metabolites belonging to the flavonoid group in the most active fractions. Overall, the results suggest that extracts from Eucalyptus globulus and Psidium guajava leaves possess antioxidant and antibacterial activities that may represent promising candidates for further investigation as plant‐derived antimicrobial agents for aquaculture systems. However, additional studies, including in vivo validation, toxicity assessment, and formulation development, are required before practical application.
Abstract Effective management of ammonia and nitrite remains a major challenge in intensive shrimp aquaculture, where excessive nitrogen loading compromises water quality and animal health. Indigenous microbial communities inhabiting mangrove sediments are widely considered potential sources of ammonia‐ and nitrite‐transforming microorganisms; however, their presence and functional potential remain poorly characterized. This study aimed to explore potential ammonia‐ and nitrite‐transforming microbiomes in mangrove sediments using a molecular approach that combines substrate‐driven enrichment, environmental DNA (eDNA) metabarcoding, and PICRUSt2‐based functional inference. Ammonium chloride enrichment resulted in rapid ammonium/ammonia depletion, transient nitrite accumulation, and sustained nitrate production, consistent with nitrification‐related processes. Sodium nitrite enrichment was characterized by progressive nitrite depletion and associated shifts in nitrogen transformation pathways. Both enrichment conditions led to reduced microbial diversity and substantial restructuring of community composition. ASV‐level functional attribution indicated that genes involved in ammonia and nitrite transformation were primarily associated with low‐abundance, functionally specialized taxa, including Nitrosomonas‐ and Nitrospira‐like groups. Nitrite enrichment further suggested involvement of denitrification‐associated taxa, including Pseudomonas. Functional profiles inferred using PICRUSt2 indicate potential shifts in nitrogen‐cycling pathways, although these should be interpreted as predictive rather than direct measurements of microbial activity. These findings provide molecular evidence for the presence of indigenous microbiomes with potential roles in ammonia and nitrite transformation in mangrove sediments and establish a foundation for future isolation and functional validation of candidate microorganisms for shrimp aquaculture applications.
Abstract Ammonia, a major by‐product of protein catabolism in shrimp, can rapidly accumulate in high‐density culture systems, particularly under limited water exchange. It is a common toxicant and a key limiting factor in intensive aquaculture, entering through the gills and causing metabolic disruption, reduced growth, and increased mortality. In this study, ammonia tolerance of Pacific white shrimp, Litopenaeus vannamei postlarvae (PL) (45 ± 02 mg) was investigated by a series of acute toxicity experiments at eight salinity levels (0, 1, 5, 10, 15, 20, 25, 30, and 35 ppt) at pH 8.0 and temperature of 28°C. Oxygen consumption rates (OCR) were also measured to determine the Routine metabolic rate (RMR) of the PLs at different salinity (1, 5, 15, 25, and 35 ppt) and total ammonia nitrogen (TAN) (0, 5, 10, 20, and 40 mg/L) combinations. The tolerance of the PLs to TAN and unionized ammonia (NH3) increased significantly with increasing salinity levels. The safe level of ammonia for the PLs was changed from 0.24 to 1.70 mg/L and 0.016 to 0.110 mg/L and 0.4, 1.0, and 1.6 mg/L for TAN and NH3 at the salinity levels mentioned above, respectively. At any, each salinity level, the RMR of the PLs increased with increasing TAN concentration (p < 0.01) and were 98.2, 115.1, 126.4, 134.9, and 136.2 μg O2 mg−1 h−1 at 1, 5, 15, 25, and 35 ppt, respectively, at 0 mg/L TAN concentration (p < 0.01). The results indicate that salinity, ammonia concentration, and exposure time interactively affect the survival and physiological responses of Litopenaeus vannamei PLs. Salinity was a key factor, with higher levels enhancing ammonia tolerance, while low salinity likely increased sensitivity due to osmotic stress and greater ammonia uptake.
Abstract This study evaluated the effects of dietary bixin, a carotenoid from Bixa orellana, on larval development, post‐larval performance, and carotenoid deposition in Macrobrachium amazonicum under controlled conditions. Larvae were reared in a recirculating aquaculture system with a moving bed biofilm reactor (MBBR) and fed Artemia nauplii and an inert diet. Two treatments were tested: a control diet and a diet supplemented with 1000 mg kg−1 annatto extract (172.75 mg kg−1 of bixin). Bixin supplementation increased pigmentation and astaxanthin accumulation in post‐larval tissues, indicating effective uptake and deposition of dietary carotenoids. However, at the tested inclusion level, it reduced metamorphosis rate and decreased post‐larval productivity, while total survival did not differ statistically between treatments. Additionally, post‐larvae from the supplemented group showed higher individual weight, although this result should be interpreted cautiously because it may reflect delayed developmental progression rather than improved growth performance. These findings indicate that bixin is a promising natural carotenoid source for M. amazonicum, but its effects are dependent on the inclusion level. Further studies are required to determine optimal dietary concentrations that balance pigment deposition, larval performance, and production efficiency.
Abstract Shewanella putrefaciens is an important bacterial pathogen that poses a serious threat to Chinese mitten crab (Eriocheir sinensis) aquaculture. However, the protective effects of N‐Acetylserotonin (NAS) against S. putrefaciens infection in E. sinensis remain unknown. In this study, to evaluate the protective effects of NAS while eliminating the influence of dimethyl sulfoxide (DMSO) as its solvent, the growth performance, hepatopancreatic immunity, antioxidant capacity, intestinal microbiota, and resistance to S. putrefaciens challenge were assessed in E. sinensis from the blank control, 10.0 mL/kg diet of DMSO‐treated negative control, and 10.0 mL/kg diet of DMSO +0.5 and 1.0 g/kg diet of NAS‐treated groups. The results showed no significant differences in the growth performance among crabs in the blank control, 10.0 mL/kg diet of DMSO‐treated negative control, and 10.0 mL/kg diet of DMSO +0.5 and 1.0 g/kg diet of NAS‐treated groups. The hepatopancreatic acid phosphatase, alkaline phosphatase, lysozyme, superoxide dismutase, and catalase activities of the 10.0 mL/kg diet of DMSO +0.5 and 1.0 g/kg diet of NAS‐treated crabs were significantly increased compared with the blank control. In contrast, no significant changes were observed for these enzyme activities in the 10.0 mL/kg diet of DMSO‐treated negative control crabs. Furthermore, the 10.0 mL/kg diet of DMSO +0.5 and 1.0 g/kg diet of NAS‐treated crabs exhibited a notable improvement in the richness and diversity of intestinal microbiota and displayed survival rates of 36.67% and 60.00%, which were significantly higher than the blank control and 10.0 mL/kg diet of DMSO‐treated negative control groups. Collectively, these findings reveal that NAS shows great promise as a potential prophylactic agent for health maintenance and disease prevention in crab culture.
Abstract This study aimed to identify species compositions that use resources more efficiently and recommend management practices for extensive and semi‐intensive pond polyculture by modeling food webs and calculating performance indicators. We monitored 8 polyculture fish ponds managed by fish farmers that had contrasting fish species compositions in two regions of France and analyzed their biomass flows using the Ecopath model. The ponds that had been stocked with at least 5 species × size classes had the highest net fish yield and nutrient recycling (Finn cycling index [FCI]), which highlighted the importance of diversity and complementarity for increasing resource use, nutrient recycling, and productivity. Carnivorous fish appeared to contribute significantly to net fish yield and nutrient recycling. Ponds stocked with grass carp had significantly higher mean net fish yield, likely because the grass carp occupied an otherwise vacant trophic position. Ecotrophic efficiency (EE) was high for benthic macroinvertebrates (0.90–0.99) and zooplankton (0.55–0.99), which indicated that they can limit pond productivity, but low for phytoplankton and detritus (0.06–0.29 and 0.04–0.17, respectively), which indicated that they were underconsumed. FCI was not significantly correlated with net fish yield but was significantly correlated with the EE of phytoplankton (r = 0.90) and detritus (r = 0.91), which highlighted the importance of these functional groups to nutrient recycling. This study provides insights into biomass flows among species during a production cycle, which could be improved by modeling temporal dynamics of the system. It indicates that nutrient recycling and productivity in fish ponds can be increased by defining the percentages of species more precisely.
Abstract Snakehead rhabdovirus (SHRV) is a novirhabdovirus associated with disease outbreaks in warm‐water fish in Southeast Asia, including striped snakehead (Channa striata), but recent information on SHRV in Thai snakehead aquaculture remains limited. In May 2024, high mortality was reported in cultured snakehead from multiple farms in Suphan Buri, Thailand. Necropsy and histopathology results revealed severe, multifocal necrosis in the kidney, spleen, heart, and skin, consistent with a systemic viral disease. Virus isolated from pooled liver–spleen homogenate was propagated in E‐11 cells, and reverse‐transcription PCR identified the agent as SHRV. Transmission electron microscopy showed bacilliform virions approximately 180–200 × 60–70 nm. Following ultracentrifugation and sucrose purification, SDS‐PAGE resolved four dominant viral proteins consistent with glycoprotein (G), nucleoprotein (N), phosphoprotein (P), and matrix protein (M), which were further confirmed by LC–MS/MS. Partial genome sequencing and analysis identified six coding regions (N, P, M, G, NV, L), and sequence comparison revealed amino acid differences relative to a previously reported regional SHRV strain (GenBank Accession NC_000903.1). SHRV‐containing supernatants produced marked cytopathic effects in E‐11 cells at a 10−10 dilution within 24 h, and the purified virus was successfully titrated by plaque assay. Collectively, these findings document the re‐emergence of SHRV in Thailand after more than two decades and provide a contemporary isolate with pathological, molecular, ultrastructural, and proteomic characterization to support improved surveillance, diagnostics, and farm biosecurity in snakehead aquaculture.
Abstract The red swamp crayfish (Procambarus clarkii) is widely cultured and consumed due to its palatable meat and high nutritional value. It also becomes the most valuable crustacean species because of its amazing yield and economic value in China. However, P. clarkii has unique reproductive habits, such as multiple mating events, low fecundity, asynchronous sexual maturity, and egg‐carrying hatching, which pose huge challenges to its seed breeding and genetic improvement. Additionally, the large‐scale breeding technology of P. clarkii has not achieved a substantial breakthrough. The scarcity of high‐quality seedlings and the problem of periodic juvenile supply hinder the further development of the P. clarkii aquaculture industry. This research adopted a systematic literature review approach, combining thematic analysis with quantitative synthesis of data from published articles (1972–2025), and contacting with production practice, we briefly describe the research advances including the reproduction biology and artificial breeding techniques in P. clarkii, and analyze some main factors which influence the reproduction and production of P. clarkii, including shelters, light, water temperature, salinity, and drought stress. Our analysis reveals that the key to the artificial breeding techniques in P. clarkii lies in effectively promoting synchronized spawning and producing P. clarkii juveniles in a large‐scale way. To achieve the breeding of high‐quality seedlings, the breeding of fine varieties of P. clarkii will be put on the crucial agenda in the future. Similar to other aquatic animals, with the assistance of various molecular biology techniques, the breeding will be more precise and efficient.
Abstract Diet selection, stocking density, and target levels for dissolved oxygen concentration are three of the major management decisions made by aquaculture producers. These factors and their combinations were tested in channel catfish (Ictalurus punctatus) to determine their relative impact on food conversion ratio (FCR), growth performance, and proximate analyses after 8, 16, and 22 weeks of feeding to satiation in indoor tanks at 26.7°C and processing traits after 22 weeks. At the end of the study, catfish grew from 29 to 732 g with an FCR of 1.1 in the best performing treatment combination (high protein, high dissolved oxygen concentration, low density) and from 29 to 414 g with an FCR of 1.2 in the worst performing treatment combination (low protein, low dissolved oxygen concentration, low density). After each sample period, the high protein diet significantly decreased FCR and growth, stocking density had no impact on any recorded variable, and low dissolved oxygen concentration reduced appetite but also decreased FCR. As fish grew, FCR increased and feed consumption as a proportion of body mass decreased. All factors tested had little impact on proximate analyses, but the high protein diet consistently had worse protein conversion efficiency (PCE). Higher feed protein decreased both headed‐gutted and fillet yield, but no other factor had an effect. In channel catfish, higher feed protein improves growth, FCR, and meat yield; higher dissolved oxygen concentration increases appetite; and stocking density has no impact on performance if oxygen is maintained at saturation.
Abstract To elucidate the pathogen and host response mechanisms underlying mass mortality in Quasipaa spinosa, dominant bacteria were isolated from diseased individuals and identified as Citrobacter freundii by morphological, physiological, and biochemical characterization, 16S rRNA sequencing, and phylogenetic analysis. The median lethal dose (LD50) of this bacterium for Q. spinosa was determined to be 4.65 × 105 CFU/mL through experimental infection. The histopathological examination revealed that the liver showed significant vacuolar degeneration, necrosis, and thrombosis. Transcriptome sequencing identified 2404 differentially expressed genes (DEGs) (1338 up‐regulated and 1066 down‐regulated). DEGs were significantly enriched in protein processing in the endoplasmic reticulum, cytochrome P450‐mediated xenobiotic metabolism, and the PPAR signaling pathway. Key immune genes (HSP70 and Bax) were markedly up‐regulated, whereas the negative regulator (TRIM25) was down‐regulated. Reverse Transcription Quantitative PCR (RT‐qPCR) validation was highly consistent with the RNA‐seq data. This study systematically revealed how Q. spinosa resists C. freundii infection by activating innate immunity, apoptosis, and metabolic reprogramming, providing theoretical insights and candidate molecular targets for the prevention and control of bacterial diseases in amphibians.
Abstract Fish health significantly influences aquaculture productivity, sustainability, food security, and public health. Despite Ghana's rapid aquaculture expansion, the sector remains constrained by widespread disease outbreaks and environmental threats. This systematic review synthesizes existing literature (2010–2024) to comprehensively assess fish health issues, management practices, diagnostic capabilities, environmental threats, and policy implications in Ghana. Following PRISMA guidelines, 65 eligible studies were selected from an initial 386 records and critically appraised using the Mixed Methods Appraisal Tool (MMAT). Findings indicate that bacterial pathogens (notably Streptococcus and Aeromonas spp.), viral infections such as Infectious Spleen and Kidney Necrosis Virus (ISKNV), parasitic infestations, and emerging fungal pathogens constitute major disease threats. Environmental stressors such as heavy metals, pesticides, and microplastics were frequently detected in aquaculture‐associated water bodies, raising ecological and food safety concerns. Although molecular diagnostic tools are increasingly being adopted, national diagnostic coverage remains uneven. Widespread antibiotic misuse, weak biosecurity implementation, and regulatory gaps further exacerbate fish health risks. This review provides the first integrated synthesis linking disease epidemiology, environmental contamination, diagnostic capacity, farmer practices, and governance challenges within Ghana's aquaculture sector. Strengthening surveillance systems, improving diagnostic infrastructure, enhancing farmer training, and enforcing regulatory frameworks are essential to improving resilience and sustainability. The findings offer policy‐relevant insights applicable to emerging aquaculture systems across sub‐Saharan Africa and other developing regions.
Abstract Viral diseases are a major concern in finfish aquaculture, leading to severe health problems. Infectious hematopoietic necrosis (IHN) is a highly transmissible systemic viral disease that primarily affects salmonids, causing significant mortality and economic losses to the salmonid farming industry. This review covers all major aspects of the virus, including its morphology and structure, replication cycle, geographical distribution, transmission, susceptibility and ultrastructural analysis. It also provides a comprehensive phylogenetic analysis of IHNV strains, specifically focusing on the G, N, M and NV genes, underscoring the importance of developing vaccines that are genetically aligned with circulating viral variants to improve immunization efficacy. In addition, this review addresses disease progression, prevalence, immunological responses, host range, clinical and histological appearance, diagnostic methods, control and management strategies, including current vaccine options. Molecular mechanisms of IHNV pathogenesis are discussed with particular emphasis on glycoprotein G as a key target for neutralizing antibodies and vaccine development. A detailed understanding of IHN and its prevention is essential for maintaining healthy aquaculture stocks, supporting sustainable production and meeting global demand for fish and fish‐derived products.
Abstract This study aimed to evaluate the effects of dietary 1,8‐cineole (CIN) on Nile tilapia, Oreochromis niloticus, reared at different stocking densities. Fish (average initial weight 13.2 ± 0.35 g) were fed diets supplemented with 0%, 0.25%, or 0.5% CIN and stocked at either 14 (normal) or 56 (high) fish per 120‐L tank. The fish were reared for 8 weeks in triplicate and fed the diets at a rate of 4% per day. The results showed no significant interaction effects between dietary CIN and stocking density for any of the parameters tested. Also, there were no significant differences between 0.25% and 0.5% CIN treatments in any tested parameters. Dietary CIN and stocking density had no significant effects on feed efficiency and fish growth rate, plasma cortisol, and glucose levels. Dietary CIN significantly increased the plasma total antioxidant capacity and hepatic superoxide dismutase activity, but decreased hepatic malondialdehyde levels. The increase in fish stocking density significantly increased the plasma total antioxidant capacity and hepatic malondialdehyde levels. Dietary CIN and stocking density had no significant effect on the hepatic catalase activity. Dietary CIN significantly increased skin mucus alkaline phosphatase and plasma alternative complement activities, but fish stocking density had no significant effect on these parameters. Dietary CIN significantly increased lysozyme activities and immunoglobulin levels in plasma, skin mucus, liver, and kidney. The increase in fish stocking density significantly decreased lysozyme activities in plasma, skin mucus, and liver, but increased the kidney lysozyme activity. Moreover, the increase in fish stocking density significantly increased immunoglobulin levels in the liver and skin mucus, but decreased them in the plasma. In conclusion, this study demonstrates that an increase in stocking density up to 56 fish per 120‐L tank had no detrimental effect on feed efficiency and growth performance of Nile tilapia. Also, dietary CIN does not affect Nile tilapia growth but boosts antioxidant and immune systems, which may improve fish welfare and resilience. Hence, dietary 0.25% CIN supplementation is recommended for Nile tilapia feed formulation.
Abstract As climate change reshapes agriculture and food systems across the globe, aquaculture in sub‐Saharan Africa (SSA) is at a turning point. Sustainable climate‐smart aquaculture (SCSAq) aims to make fish farming more productive, resilient to climate change, and environmentally friendly while also improving livelihoods and nutrition. This review collates and consolidates empirical findings on how SCSAq is being adopted across the region and what factors are driving or hindering its scalability. Drawing from recent studies (2015 to 2025), this paper identified key practices being used, such as recirculating systems, organic inputs, local feed production, and water‐saving techniques. The paper also synthesizes existing findings on factors influencing uptake such as education, access to finance, institutional support, and environmental conditions. Major barriers such as high start‐up costs, poor infrastructure, and limited knowledge were also identified. Finally, the wide impacts of SCSAq is discussed, showing how it can improve food security, incomes, and ecosystem health if effectively scaled up. This review highlights the need for inclusive policies, farmer‐led innovation, and cross‐sector collaboration to bridge the gap between science, policy, and practice. With the right support, SCSAq can play a significant part in building a more sustainable and climate‐resilient pathway for aquaculture in SSA.
Abstract This study evaluated hatching rate, survival, osmolality, hematological and histopathological parameters to identify the optimal salinity of golden rabbitfish (Siganus guttatus) at three life stages: embryonic, pre‐feeding larvae, and juvenile. The study was conducted using a series of salinity treatments ranging from 10 to 40 ppt, assessing the hatching rate and egg osmolality during the embryonic stage, survival and plasma osmolality in pre‐feeding larvae, and survival, plasma osmolality, hematological parameters, and histopathological changes in juveniles over 14 days. The results showed that the highest hatching rate (73%) occurred at 20 ppt, with egg osmolality increasing with salinity, indicating an evolved osmoregulatory mechanism. At the pre‐feeding larval stage, survival was highest at 20 ppt (32%) and decreased with lower and higher salinities. Juvenile survival was high at all experimental salinities, although stress was evident at salinities exceeding 30 ppt, based on daily stress scores (body color and behavior) and histopathological observations. Histological analysis revealed minimum tissue damage in gills, liver, and kidneys at 30 ppt but higher abnormalities at higher and lower salinities. The findings suggest that maintaining salinity between 20 and 25 ppt optimizes hatching and survival rates during the early life stages, while salinity between 10 and 35 ppt is optimal for juvenile rearing. These results have implications for improving hatchery practices and juvenile rearing of golden rabbitfish.
Abstract Cholecystokinin receptor (CCKR), an important recognition receptor for the gastrointestinal hormone cholecystokinin (CCK) in the endocrine system, plays a crucial role in regulating immune responses in mammals. In this study, a novel cholecystokinin receptor (CiCCKR) was identified from the grass carp Ctenopharyngodon idella. Similar to other reported CCKR proteins, CiCCKR features seven transmembrane helical domains, an ERY motif located in transmembrane region III, and a NPIIY motif found in transmembrane region VII. Expression profiling indicated that CiCCKR was primarily expressed in the brain, with a lower level of expression in the intestine. Phylogenetic analysis revealed that CiCCKR belonged to the fish cluster and showed the closest relationship to Megalobrama amblycephala. In vivo injection experiments demonstrated that CiCCK and CiCCKR exhibited a strong response to stimulation with Aeromonas hydrophila, Aeromonas veronii, and Muramyl Dipeptide (MDP), with expression levels significantly up‐regulated in the intestines of grass carp. In cases of intestinal inflammation induced by MDP, CCK can significantly decrease the expression levels of inflammatory factors (CiTNF‐α, CiIL‐1β, CiIL‐8) and the CiPepT1/CiNOD2 pathway (CiPepT1, CiNOD2, CiRIP2), while expression levels of the genes in the CiCCKR pathway (CiCCKR, CiGNAS) are significantly up‐regulated. In vitro and in vivo experiments indicated that knocking down CiCCKR and treating with its inhibitor proglumide effectively regulated MDP‐induced intestinal inflammation by activating the CiPepT1/CiNOD2 pathway. Overall, these findings suggested that CiCCKR may play a critical role in the intestinal immune response to bacterial challenges.
Abstract Accurate sex identification is essential for aquaculture, breeding management, and conservation, particularly in species lacking external sexual dimorphism during early development. Softshell turtles (family Trionychidae) are of high economic importance: their meat is prized in markets, their shells are used in traditional medicine, and large‐scale farming supports rural economies. Male Chinese softshell turtles grow faster than females; therefore, developing reliable sex identification methods for these species is critical. Softshell turtles possess evolutionarily stable ZZ/ZW sex chromosomes, which provide a strong genomic foundation for molecular sexing. In this study, we developed a PCR‐based method for molecular sexing across 5 Trionychidae species, targeting intronic sequence variation in the Ran gene. A single band (~250 bp) is amplified in ZZ males, while two distinct bands (~250 and ~600 bp) are produced in ZW females, due to size differences in the second intron. This diagnostic pattern enables clear and reliable sex identification. Using this method with a conserved primer pair, we successfully sexed individuals of the Chinese softshell turtle (Pelodiscus sinensis), Spiny softshell turtle (Apalone spinifera), and Florida softshell turtle (Apalone ferox). The assay is rapid and cost‐effective and offers a cross‐species approach for molecular sexing across softshell turtle lineages and a practical tool for aquaculture, selective breeding, and conservation genetics.
