Microplastic pollution has emerged as a major environmental concern in rapidly urbanising and industrialised ecosystems. This study investigated the spatial and seasonal distribution and ecological risk assessment of microplastics in the Ennore coastal waters of southeast India covering Thalankuppam, Kattupalli, and Ennore Beach across six sampling seasons from monsoon 2024 to post-monsoon 2026. Microplastics were isolated, followed by stereomicroscopic characterisation based on shape, colour, and size. Polymer composition was confirmed using ATR–FTIR spectroscopy, and ecological risk was assessed using the contamination factor (CF), pollution load index (PLI), polymer hazard index (PHI) and potential ecological risk index (PERI). Microplastic abundance ranged from 85 to 215 particles L–1, with the highest seasonal recorded during post-monsoon 2025 (185 particles L–1) and the lowest during summer 2025 (95 particles L–1). Spatially, Kattupalli (110–215 particles L–1) consistently recorded the highest microplastic abundance. Fragments and foam were the dominant morphotypes, while black and blue particles predominated among the colour classes. The 0.5–1 mm size fraction was the most abundant, suggesting extensive secondary fragmentation. ATR–FTIR analysis identified polyethylene (28–32%) and polypropylene (15–18%) as the dominant polymers, indicating packaging materials, fishing gear, and urban plastic waste as major sources. Risk assessment revealed moderate to considerable contamination (CF: 2.12–3.04), low pollution load (PLI: 1.46–1.78), very high polymer hazard (PHI: 5789–7293) and minor ecological risk (PERI: 57.89–72.93). These findings provide baseline information for monitoring microplastic pollution and support effective management strategies for the Ennore coastal ecosystem.
The Irrawaddy mangrove ecosystem in Myanmar is a crucial habitat for aquatic biodiversity, yet its ecological dynamics remain understudied. This research explored the seasonal variation, spatial dynamics, and trophic structure of fish assemblages in Pyapon and Bogale townships, Myanmar. Seasonal and market surveys recorded 129 fish species from 64 families, with Mystus gulio, Oryzias dancena, Coilia dussumieri, and Glossogobius giuris dominating the community. Seasonal shifts significantly influenced species diversity. Winter exhibited the highest species richness and diversity, while summer displayed the lowest. Nevertheless, species evenness remained highly stable across all seasons, suggesting a consistently balanced community. Moving beyond basic water parameters, multivariate analyses demonstrated that habitat complexity and food web dynamics are likely key drivers of community structuring. Permutational multivariate analysis of variance revealed a highly significant spatial separation of fish assemblages between mangrove and agricultural land habitats. Furthermore, indicator species analysis identified specific taxa driving this divergence, while functional feeding guild analysis revealed a marked dominance of benthivores and detritivores in mangrove sites. This highlights the critical role of mangrove-derived organic matter in supporting the estuarine food web. The presence of four threatened species, including the Endangered Eleutheronema tetradactylum and Johnius macrorhynus, demonstrates that preserving the physical integrity and trophic inputs of mangroves is paramount for sustaining estuarine fish diversity and supporting sustainable local fisheries management.
The present investigation provides the first comprehensive account of food and feeding habits of 375 Endangered putitor mahseer, Tor putitora, from Rajouri River of the Pir Panjal Himalayan region. Food items were grouped into eight categories, namely macroinvertebrates, zooplanktons, algal matter, unidentified plant matter, fish remains, detritus, unidentified-debris, and mud and sand, which were broadly classified into three major groups- plant matter, animal matter and miscellaneous materials. Quantitative and qualitative analyses revealed that plant matter constituted 38.97% of the diet, followed by miscellaneous materials 34.16% and animal matter 26.75%. The gastro somatic index and fullness index varied with sex, maturity stage and season owing to changes in food availability and reproductive activity. Both indices were the lowest during the spawning stage and highest during the pre-spawning stage. Feeding intensity increased during maturation and ripening (stages III and IV), but decreased significantly during the ripe stage (stage V). The relationship between total length and gut length indicated that gut was longer than the body, with body length-to-gut length ratios were 1:1.50 in females and 1:1.65 in males. Overall, relative length of gut, the index of preponderance, and predominance of algal matter throughout the year, together with the occurrence of animal matter in the gut indicate that the T. putitora is a column-feeding omnivore. These findings provide baseline information on the feeding ecology of this threatened species and will be valuable for the development of captive breeding, habitat management and conservation strategies.
India is one of the world's leading exporters of marine products, contributing substantially to foreign exchange earnings, employment, and coastal livelihoods. Understanding long-term export growth, market transitions, and future trade prospects is essential for strengthening export competitiveness and policy planning. This study analysed India's marine product exports using secondary data from 2005–2006 to 2024–2025 covering eight product groups (frozen shrimp, frozen fish, frozen cuttlefish, frozen squid, dried items, live items, chilled items, and others) and seven major export markets. Export growth, instability, market concentration, market transition, and future export trends were evaluated using Compound Annual Growth Rate (CAGR), Cuddy–Della Valle Instability Index (CDVI), Herfindahl–Hirschman Index (HHI), Markov Chain analysis, and Auto-Regressive Integrated Moving Average (ARIMA) models, respectively. The results indicated that frozen shrimp remained the dominant export commodity, while China recorded the highest growth with comparatively high instability. Markov Chain analysis revealed a structural shift in export market retention, with the United States of America (USA) emerging as the most stable destination during the later period. ARIMA forecasts indicated a gradual decline in export values across most product categories through 2035 under existing trends. The findings suggest the need for export diversification, value addition, and market expansion to enhance the long-term resilience and competitiveness of India's marine products sector
The marine ornamental fish industry is a global multi-million-dollar trade dealing in live fish and other marine organisms for aquariums. This industry has seen significant growth in recent years; however, it still relies heavily on wild populations. Pomacentridae is the family that contributes most to the worldwide marine ornamental fish trade. This forms the first report on the captive breeding and egg development of Allen’s damsel or Andaman damsel, Pomacentrus alleni Burgess, 1981. Captive breeding and egg development of the wild-caught specimens of Andaman damselfish was conducted in the Vizhinjam Regional Centre of ICAR-CMFRI. The wild-collected broodstock required four months to achieve the first successful spawning. Fecundity observed was from 1070±127 eggs from a female brooder of 5.7 cm TL. The eggs were capsule shaped, measuring 856.91±66.61 µm, with a single oil globule. Hatching rate was 90.6±1.9%. The incubation time was recorded as 107±7.1 hr. Newly hatched larvae had a total length of 1.84±0.11 mm; standard length 1.65±0.03 mm. The present study evaluated the broodstock development and spawning potential of P. alleni under captive conditions, providing insight into the sustainable use of such marine fish resources.
Dragon fruit peel, an agro-industrial by-product, has gained considerable attention across various sectors, including aquaculture, due to its rich composition of functional compounds beneficial to aquatic animals. This review focuses on the major bioactive phytochemicals present in dragon fruit peel, namely phenolic compounds, flavonoids, tannins, and betalains, along with the essential nutrient vitamin C. It provides a comprehensive overview of these components, including their chemical characteristics and functional roles in fish nutrition when incorporated into diets. In addition, the effects of dragon fruit peel supplementation in aquaculture are discussed based on findings from various studies to enhance current understanding. Collectively, these bioactive constituents have been reported to improve growth performance, enhance feed utilization, strengthen antioxidant defence systems, and promote intestinal health through modulation of gut microbiota and immune-related pathways.
Sustainable seed production of genetically selected growth-trait Clarias magur is a promising candidate for aquaculture diversification due to its superior growth rate and adaptability. However, it is a significant challenge to raise the quality of male brooders in captivity for commercial-scale seed production. The present study aimed to evaluate the effects of marine algal oil, Schizochytrium limacinum (SMAO), on growth performance, reproductive development, and testicular histoarchitecture of genetically selected growth trait (SGT) Clarias magur males through supplementation in broodstock diets at four different levels (SMAO 2%, SMAO 3%, SMAO 4%, and SMAO 5%), with fish oil (FO 3%) serving as the control, in a completely randomised design using 15 circular FRP tanks of 1000 L capacity, each holding 15 fish (ten males and five females) with a mean standard length of 24.3±0.86 cm and a mean weight of 96.04±4.14 g fish fed with 5% of body weight for 90 days. The SMAO 4% diet resulted in the highest weight gain (16.50±2.1 g) with the lowest feed conversion ratio (2.23±0.65). The highest gonad weight (0.55±0.12 g), gonadosomatic index (0.52), and abundant spermatozoa in the testis histology were observed in the SMAO 5% diet. The sperm density varied across SMAO treatments and the FO group, and higher spermatocrit value (94.39%) and sperm density (14.40×109 cells mL–1). In conclusion, SMAO supplementation at 4% enhances growth and captive maturation in male SGT magur, while 5% SMAO promotes higher sperm cell abundance in testes, supporting its use in sustainable broodstock development.
The increasing demand for sustainable and functional feed additives in aquaculture has driven interest in agro-industrial by-products such as orange (Citrus sinensis) peel, which are rich in bioactive compounds. This study investigated the effects of dietary orange peel supplementation on growth performance, digestibility, physiological responses, and disease resistance in goldfish Carassius auratus. Fish were fed diets containing 0% (control), 2.5%, 5%, and 7.5% orange peel for 60 days, followed by analyses of growth, digestive enzymes, haematological, biochemical, immunological parameters, and a pathogen challenge test. Results showed that the 2.5% inclusion level significantly enhanced growth, with approximately two-fold higher weight gain and improved feed conversion ratio (ANOVA: p < 0.05). Protein digestibility increased by ~20% in 2.5% and 5% groups, while digestive enzyme activities, particularly amylase (~120% increase) and protease (~25% increase), were markedly elevated. Haematological indices (RBC, HB, HT) improved significantly (p < 0.001), while glucose, triglycerides, and cholesterol were reduced in higher inclusion groups (p < 0.001). Antioxidant (SOD, CAT) and immune responses (NBT, MPO) were significantly enhanced (p < 0.001), indicating improved oxidative stress resistance and immune competence. Carotenoid deposition increased significantly in muscle (~24%) and skin (~23%). Following Aeromonas hydrophila challenge, survival improved up to 1.7-fold in supplemented groups (p < 0.05). Overall, the results demonstrate that orange peel, particularly at 2.5% inclusion, serves as an effective, sustainable functional feed additive that enhances growth, physiological health, and disease resistance, offering practical implications for improving aquaculture productivity and resilience.
Aeromonas veronii is an important etiological agent of motile aeromonas septicemia (MAS) in aquaculture; however, its pathogenicity in the emerging cultured species red-bellied pacu (Piaractus brachypomus) remains poorly understood. Pacu fingerlings (10±2 g; n = 180) were intraperitoneally challenged with A. veronii strain BLB-01 (GenBank accession: MF370515) at concentrations ranging from 10⁵ to 10⁹ CFU mL⁻¹, following OECD guideline 203. The median lethal dose (LD₅₀) was estimated using probit analysis. Clinical signs, haematological and biochemical parameters, and histopathological alterations were evaluated at 96 h post-LD₅₀ exposure. Probit analysis (Y = 0.591 + 2.185 log₁₀ concentration; R² = 0.984) estimated the LD₅₀ as 7.8×10⁶ CFU mL⁻¹ (95% CI: 5.2–11.4 ×10⁶ CFU mL⁻¹). Infected fish exhibited progressive MAS symptoms over 7 days. Haematological analysis revealed significant anaemia (decreased haemoglobin and total erythrocyte count), leukocytosis (increased total leukocyte count), and thrombocytopenia (reduced platelet count). Biochemical changes included stress-induced hyperglycaemia (elevated glucose), hepatocellular damage (increased ALP, AST, and ALT), and hypoalbuminemia (reduced albumin). Histopathological examination demonstrated severe lesions, including gill lamellar fusion (2.8±0.3), hepatic vacuolation (2.9±0.2), and renal tubular necrosis (2.8±0.2). Aeromonas veronii exhibits high pathogenicity in pacu, with an LD₅₀ of 7.8×10⁶ CFU mL⁻¹, providing baseline data for challenge studies and the development of vaccines and probiotics. A combination of haematological and biochemical markers particularly increased TLC, reduced platelet count, and elevated liver enzymes offers a practical tool for rapid field-level diagnosis and surveillance of MAS, supporting improved health management in Indian pacu aquaculture.
Coastal tourism is increasingly recognized as a vital component of the global 'blue economy', offering a critical pathway for traditional fishing communities to diversify their livelihoods amid mounting economic and environmental pressures. To understand this dynamic, this study investigates the occupational transition of 120 coastal fisherfolk into the tourism sector across two states in India. Analyzing socio-economic profiles and transition patterns, the research highlights a significant occupational shift, with 85.8% of respondents now identifying tourism as their primary income source. Demographically, the participants are predominantly middle-aged males with low educational attainment and modest living conditions. Fisherfolk strongly favor tourism over traditional fishing, citing lower physical strain, reduced risk, and more stable earnings. Consequently, this transition has led to a marked reduction in fishing labor hours and a significant income boost, with median annual tourism earnings reaching ₹252,000 (~USD 2610). Furthermore, data models reveal that a willingness to step away from traditional fishing is the strongest predictor of transition readiness. Despite these positive economic outcomes, the occupational shift is hindered by several major constraints. Disruptions from the COVID-19 pandemic, high initial investments, strong competition from established operators, poor infrastructure, and adverse weather conditions remain significant challenges. Ultimately, while tourism is increasingly central to diversifying coastal livelihoods and reducing heavy physical labor, ensuring its sustainability requires targeted interventions. Stronger institutional support, comprehensive skill development, and accessible financial mechanisms are essential to secure equitable, long-term benefits for these coastal communities.
Sperm cryopreservation is widely used in aquaculture for long-term preservation of genetic resources and broodstock management; however, prolonged storage can adversely affect sperm quality due to structural damage and ionic imbalance. This study evaluated the influence of L-proline supplementation, with and without dimethylsulfoxide (DMSO), on the cryopreservation efficiency of Piaractus brachypomus sperm. Milt from hormonally induced males was cryopreserved in Modified Cortland Medium (MCM) supplemented with 2, 5, 10, and 30 mM L-proline, either in the absence of DMSO or in combination with 10% DMSO, and maintained under liquid nitrogen for 90 days. Sperm quality after thawing was evaluated at 15-day intervals. Significant differences were observed in sperm motility and viability among treatments. Among the MCM supplemented with L-proline treatments, 10 mM L-proline maintained the highest post-thaw sperm motility (58.05–53.40%) and viability (62.50%), whereas the MCM without cryoprotectant showed the lowest values. Among the MCM containing 10% DMSO treatments, 10% DMSO and 10% DMSO + 2 mM L-proline maintained comparatively higher post-thaw sperm motility (54.36–51.04% and 56.44–49.75%, respectively), whereas other groups exhibited higher post-thaw sperm viability (>52%) than the other DMSO-based treatments. Although a progressive decline in sperm quality was observed over the 90-day storage period, L-proline-supplemented groups maintained superior functional performance. Morphological assessment showed better preservation of sperm head integrity and fewer structural abnormalities in the 10 mM L-proline treatment compared to other cryopreserved treatments. The findings indicate that supplementation with 10 mM L-proline enhances sperm membrane stability and overall cellular function during cryostorage.
The present investigation was carried out for a period of 75 days to evaluate the effects of dietary supplementation of L-ascorbic acid and L-leucine on growth performance and feed utilisation in Labeo catla fingerlings. A total of nine experimental diets were formulated with different levels of L-leucine and L-ascorbic acid, including a control (T₀) without supplementation. The treatments consisted of T₁ (10 g L-leucine), T₂ (15 g L-leucine), T₃ (0.3 g L-ascorbic acid), T₄ (0.4 g L-ascorbic acid), T₅ (0.3 g L-ascorbic acid + 10 g L-leucine), T₆ (0.4 g L-ascorbic acid + 10 g L-leucine), T₇ (0.3 g L-ascorbic acid + 15 g L-leucine) and T₈ (0.4 g L ascorbic acid + 15 g L-leucine). The results indicated significant improvement in the highest final weight (3.86±0.38 g), specific growth rate (1.95±0.10% day–1), and protein efficiency ratio (1.74±0.08), along with the lowest feed conversion ratio (1.93±0.09) in T₆. The combination of 0.4 g L-ascorbic acid and 10 g L-leucine (T₆) was found to be the most effective and is recommended for enhancing growth and feed utilisation in L. catla fingerlings.
The increasing incidence of bacterial diseases in aquaculture necessitates the development of sustainable immunostimulatory strategies as alternatives to antibiotics. The present study evaluated the immunomodulatory and growth-promoting effects of indigenous herbal feed additives on common carp (Cyprinus carpio) challenged with Aeromonas hydrophila. Fish were fed diets supplemented with neem (Azadirachta indica), tulsi (Ocimum sanctum), and their combination for 90 days under controlled conditions, followed by bacterial challenge. Hematological parameters, including hemoglobin (Hb), red blood cell (RBC) count, total leukocyte count (TLC), and packed cell volume (PCV), along with growth indices such as specific growth rate (SGR), weight gain, and feed conversion ratio (FCR), were evaluated. Results showed a significant improvement in hematological and immune parameters in all treated groups compared to control, with the combined supplementation (neem + tulsi) exhibiting the most pronounced effects. The highest Hb, RBC, TLC, and PCV values were observed in the combination group, indicating improved oxygen transport capacity and immune competence. Growth performance was also significantly improved, as indicated by higher SGR and weight gain and lower FCR. Following bacterial challenge, treated groups exhibited increased resistance and survival, confirming the protective role of herbal supplementation. The findings demonstrate that dietary inclusion of indigenous herbal additives, particularly in combination, effectively enhances innate immunity, hematological health, and growth performance in common carp (Cyprinus carpio). This study highlights the potential of phytogenic feed additives as eco-friendly and sustainable alternatives for disease management in aquaculture systems.
The increasing demand for seaweed-based foods has created interest in developing sustainable alternatives to conventional Porphyra-based nori using tropical seaweed resources. This study developed a nori-like product from Halymenia dilatata and evaluated the effects of glycerin concentration and drying conditions on its nutritional, physicochemical, structural, and sensory properties. Four formulations were prepared using a constant seaweed-to-water ratio (1:10, w/v) with varying glycerin concentrations. The formulation containing 2.5% glycerin and dried at 55°C for 2 h produced sheets with the best pliability, uniformity, and handling characteristics. The optimized product contained low moisture (7.84%), moderate protein (11.62%), high dietary fibre (31.54%), and a mineral-rich ash content (14.87%), with appreciable levels of iron and zinc and a balanced sodium-to-potassium ratio. Sensory evaluation indicated good consumer acceptance for appearance, flavour, texture, and overall acceptability. Structural analyses confirmed the formation of a cohesive polysaccharide network, while biochemical and microbiological analyses demonstrated favourable quality, oxidative stability, and microbial safety. These findings demonstrated that H. dilatata could be successfully developed into a nutritious, safe, and acceptable nori-like product with physicochemical characteristics comparable to those of conventional nori, highlighting its potential as a sustainable tropical alternative for value-added seaweed-based food products.
Microplastics (MP) have emerged as one of the most persistent contaminants in aquatic habitats, infiltrating even the most ecologically sensitive systems, such as lagoons and coastal waters, where ongoing anthropogenic inputs exacerbate their accumulation and biological impact. Pulicat Lake, India's second-largest brackish water lagoon, is especially vulnerable to MP loading from tidal exchange, household waste, and fishing activities. This study examined the physicochemical properties, seasonal abundance, and ecological danger of MP at three typical stations: Goonankuppam (Station I), Thonirevu (Station II), and Pulicat Beach (Station III) from 2024 to 2025. MP abundance ranged from 50 to 135 particles L–1, peaking in Thonirevu during post-monsoon. This pattern was driven by accelerated monsoon runoff and water resuspension in the aftermath of cyclone Fengal (25 November 2024). Fibres (50.9% at Station I, 40.6% at Station II, and 51.1% at Station III) were the dominating morphotype, followed by fragments (22.60% at Station I, 27.40% at Station II, and 24.20% at Station III). The size fraction of 100–500 µm (56% at Station I, 49% at Station II, and 47% at Station III) was consistent across all locations, indicating advanced secondary fragmentation. Blue particles (40% at Station I, 30% at Station II, and 45% at Station III) predominated, highlighting the important role of fishing gear and maritime activities. This establishes a strong baseline for targeted mitigation in this ecologically sensitive lagoon-coastal interface.
The study aimed to investigate the effects of 4-nonylphenol exposure on the expression of the vitellogenin gene (Vg) and sexual steroid hormones in male Sobaity seabream (Sparidentex hasta). A total of 78 fish individuals were randomly assigned to six tanks, receiving doses of 10, 50, and 100 µg g–1 of 4-nonylphenol, as well as 2 µg g–1 of 17β-estradiol (E2) via intraperitoneal injection. The negative control group received a solvent mixture (ethanol and olive oil) with no injections. Fish sampling for blood and liver analysis occurred on days 0, 7, and 14. After RNA extraction from liver tissue and cDNA synthesis, variations in Vg expression were analyzed in relation to the beta-actin gene. The results showed a significant increase in Vg expression in the treatment groups compared to control groups. Sequencing confirmed the presence of the Vg gene, with a fragment size of 174 nucleotides. Additionally, plasma levels of sexual steroid hormones were measured using radiomonoactivity, which revealed a decrease in testosterone levels associated with varying concentrations of 4-nonylphenol. In contrast, E2 levels in fish exposed to 4-nonylphenol increased after 7 and 14 days. The findings suggest that exposure to 4-nonylphenol activates Vg production, potentially adversely affecting puberty, sexual development, sexual behaviors, and reproductive success in Sobaity seabream.
This study examined length-weight relationships (LWRs), physiological condition, growth characteristics, recruitment pattern, probability of capture, mortality rates and exploitation status of Cirrhinus reba from the Saryu River of northern India, collected fortnightly from August 2024 to July 2025. Total length varied from 11.0 to 27.0 cm (17.974±0.142 cm), while body weight varied between 13.0 and 264.1 g (73.080±6.928 g). The LWR showed a strong correlation (r² ≥ 0.915). The Fulton’s condition factor (Kf) and relative condition factor (Kn) ranged from 1.133±0.134 to 1.366±0.237 and 0.832±0.143 to 2.025±0.23 respectively, which indicated that the fish were healthy. Growth parameters estimated through von Bertalanffy model were L∞ = 27.0 cm, K = 0.65 year⁻¹ and Φ′ = 2.67. Recruitment occurred throughout the year with a major peak during the monsoon season. Total mortality, natural mortality and fishing mortality were estimated as 1.60, 0.73 and 0.87 year⁻¹, respectively. The probability of capture analysis indicated that the length at first capture L50 of C. reba was 15.5 cm. The exploitation rate (E) 0.55 was higher than Eopt (0.50) indicating emerging overexploitation. Yield-per-recruit analysis indicated exploitation reference points of Emax as 0.62 and E0.1 as 0.48. Virtual Population Analysis revealed increasing fishing mortality with fish size, with the highest fishing mortality (F = 0.91 year⁻¹) recorded in larger individuals, indicating size-selective exploitation and potential pressure on stock sustainability. This study provides information on population and exploitation characteristics of C. reba in the Saryu River, which can be used to set reference points for sustainable fisheries management.
The use of antibiotics in aquaculture poses significant health risks to fish and consumers. Adopting and validating a standard, non-lethal, and cost-effective method to monitor fish health is essential. This study investigated the impact of fluoroquinolone antibiotic enrofloxacin (ENF) on the erythrocyte cellular and nuclear morphometric anomalies in Oreochromis niloticus. Fish were fed graded doses of ENF at 0 mg, 10 mg, 30 mg, 50 mg and 100 mg kg biomass–1 day–1 for 15 consecutive days, followed by a 21-day post-dosing observation. The results revealed significant alterations in erythrocyte morphometric characteristics, such as major and minor axes, volume, surface area, cell to nucleus ratio, and surface area to volume ratio due to dietary ENF, indicating its cytotoxicity and perilous effects on fish erythrocytes. The nucleus was shrinking more significantly than the cell under treatment-induced stress. On day 15 of dosing, the surface area to volume ratio increased in the dosing groups, except for the 10× group, which represented an adaptive response in the fish to facilitate greater area for gas exchange to occur. However, the observed dose- and time-dependent erythro-morphometry was reversible once dosing was suspended. The results showed that fish erythrometric abnormalities, a relatively unexplored area of clinical science, can serve as important biomarkers or sensitive indicators of toxicity of veterinary medicinal products in assessing the physiological health status of cultured aquatic organisms.
Photoperiod is one of the most significant environmental cues for an organism, which are also essential for controlling its growth, metabolism, and maturity. The current study used an 8-week experiment to examine the effects of photoperiod T1 (12L∶12D), T2 (18L∶6D), and T3 (6L∶18D) on mud crab (Scylla serrata) growth performance and gonadal maturation. A total of 36 healthy crabs (average initial weight 416.18±2.42 g) were fed twice daily at 10% of body weight. Crabs cultured under 6L∶18D (T3) showed the highest final weight (486.54±4.44 g), weight gain (70.45±3.92 g), specific growth rate (0.26±0.01 % day–¹), gonadosomatic index (12.06±0.20%), and hepatosomatic index (5.64±0.35%), significantly higher than T1 and T2. Digestive enzyme activities (amylase, protease, lipase) were highest in the 6L∶18D group, indicating efficient nutrient utilization. Ovarian carotenoid levels were significantly (p < 0.05) higher in 6L∶18D (0.4399±0.0640 µg mg–1). Histology revealed advanced vitellogenesis and a healthy hepatopancreas in the 6L∶18D group, while the 18L∶6D showed delayed maturation. Overall, the results indicate that among the treatment groups, the 6L∶18D improved the growth, digestion, and reproductive performance of female S. serrata. This could be used in broodstock maturation, which has a detrimental effect on wild stock, and could offer valuable insights into sustainable broodstock management.
The use of bacteriophages specific to Flavobacterium psychrophilum in aquaculture has shown promising results in controlling infections and reducing fish mortality. However, the biosafety and cytocompatibility of these phage preparations, especially under long-term exposure conditions, remain largely unexplored. In this study, bacteriophages specific to F. psychrophilum were isolated and characterized. To enhance biosafety, the phages were subjected to endotoxin reduction procedures. Endotoxin levels and phage titers were quantitatively determined before and after purification. Cytocompatibility was evaluated using the MTT assay on the mammalian cell line MCF-7 over a 120-hour exposure period. The purification process reduced endotoxin levels by 97.3%, while phage titers were preserved or increased, indicating that biological activity was maintained. Time-dependent analyses revealed that crude phage preparations caused a decrease in cell viability, with statistically significant reductions observed at 72, 96, and 120 hours (p < 0.05). In contrast, no difference in cell viability was observed in cells treated with purified phage preparations compared to the control group (p > 0.05). These findings demonstrate that the cytotoxic profile of phage preparations is determined by endotoxin content and prolonged exposure duration. This study highlights that endotoxin removal is critically important for ensuring cytocompatibility and demonstrates that endotoxin content in phage preparations used in aquaculture may lead to reduced cell viability in mammalian cells under long-term exposure conditions.
