Journal of Fisheries (University of Rajshahi)
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Modelling of 2,4-dichlorophenol, an emerging pollutant removal from water by adsorption onto sugarcane bagasse biochar using response surface methodology
No full textThis study evaluated the potential of sugarcane bagasse biochar as a low-cost adsorbent for removing 2, 4-dichlorophenol (2, 4-DCP), an emerging pollutant from water using adsorption modelling and response surface methodology. It aimed to determine optimal combinations of concentration, contact time, pH and dose for maximizing contaminant uptake in batch and column systems. Batch adsorption experiments were planned using a Box–Behnken response surface experimental design with initial 2, 4-DCP concentration (25, 50, and 75 mg L–¹), contact time (20, 40, and 60 min), solution pH (5, 7, and 9), and biochar dosage (6.25, 12.5, and 25 mg). Fixed-bed column studies were conducted under continuous flow to assess dynamic performance and breakthrough behaviour. Adsorption equilibrium, kinetics and column behaviour were analysed using standard isotherm and kinetic models, supported by surface and functional-group characterization. The optimized batch conditions produced removal efficiencies of about 95% with high monolayer adsorption capacity on a homogeneous biochar surface. The equilibrium data followed a monolayer adsorption model, while kinetic analysis indicated rapid uptake controlled primarily by surface-site availability. Column studies showed high dynamic capacity and well-defined breakthrough characteristics under the tested flow conditions. Sugarcane bagasse biochar proved to be an efficient and technically suitable material for removing phenolic contaminants such as 2, 4-DCP from water. The findings demonstrate a productive use of agro-industrial waste for water purification and support its application in practical treatment units for removing emerging pollutants in aquatic environments
An annotated checklist of ichthyofauna and associated estuarine biota of the Manakudy Estuary, southern Tamil Nadu, India
No full textThis study assessed the ichthyofaunal and associated floral diversity of the Manakudy Estuary, southwest coast of India, over a two-year period involving monthly surveys from August 2023 to July 2025. Sampling efforts were stratified across three distinct ecological zones i.e., freshwater influx region (Station 1), mid-mangrove area (Station 2), and estuarine mouth region (Station 3), utilizing traditional fishing crafts and standardized visual census methods to capture spatial heterogeneity. A total of 120 species were recorded, representing 37 orders, 62 families, and 89 genera. The order Eupercaria incertae sedis showed the highest species richness (15.83%), followed by Carangiformes (12.50%) and Clupeiformes (8.33%). Among families, Carangidae was the most dominant with 13 species. Conservation assessment revealed the occurrence of threatened species, including the Endangered honeycomb stingray (Himantura uarnak) and the Vulnerable Coromandel whipray (Brevitrygon imbricata), along with two near threatened species. These findings provide baseline information essential for long-term biodiversity monitoring, sustainable fisheries management, and conservation planning in the Manakudy Estuary
Farm to policy: Socioeconomic dynamics and occupational challenges of freshwater fish farmers in the Cauvery Delta region, Tamil Nadu
No full textFreshwater aquaculture is vital for global food security and rural livelihoods. This study examined 120 fish farmers across Thanjavur, Thiruvarur, and Nagapattinam districts in Tamil Nadu's Cauvery Delta to understand socioeconomic dynamics and constraint hierarchies shaping aquaculture development. Using structured interviews and Garrett ranking, the research revealed critical structural vulnerabilities: the farming population is predominantly male (93.3%), aging (average 45 years; 79.2% middle-aged or older), and faces future labour succession challenges despite relatively high literacy (85% educated). Low organizational participation (54.2% non-members) undermines collective bargaining capacity. Most farmers (80.8%) combine aquaculture with other occupations, reflecting income insufficiency rather than strategic diversification. With 65% representing first-generation farmers averaging eleven years' experience, aquaculture emerges as recent livelihood diversification rather than traditional practice. Landholding patterns showed 75% farm ownership averaging 3.5 acres, though 53.3% operate small farms below three acres, limiting economies of scale. Caste composition revealed predominance of marginalized communities—61.7% Other Backward Class and 27.5% Scheduled Caste—facing systematic barriers to credit, technology, and market access. Constraint analysis identified high feed costs as the primary short-term barrier across all districts, followed by insufficient credit access and inadequate extension services, while low farm gate prices emerged as the dominant long-term constraint. Findings demonstrate that effective aquaculture policies must address structural inequities rooted in caste-based exclusion, land fragmentation, organizational deficits, and market asymmetries through targeted interventions including collateral-free credit, farmer producer organizations, district-level feed cooperatives, and differentiated extension programming to transform aquaculture into dignified, profitable livelihoods
Unveiling the identity of three Parapsilorhynchus species from the Eastern Ghats: an integrative taxonomic approach
Full text linkThe identities of Parapsilorhynchus odishaensis, Mahanadhi minnow P. swaini, and P. alluriensis have been elucidated through a comprehensive integration of morphological and molecular data, specifically utilizing mitochondrial cytochrome oxidase subunit 1 (COI) sequences. Specimens collected from the type localities of P. swaini and P. odishaensis, closely resembling their initial descriptions, underwent molecular analysis and were compared to the holotype sequence of P. alluriensis. The genetic distances (K2P) observed among these three species ranged from 0.0% to 2.1%. Notably, the K2P distance between P. swaini and P. odishaensis ranged from 0.2% to 0.3%, while between P. odishaensis and P. alluriensis (holotype) is 1%, and between P. swaini and P. alluriensis (holotype), there was a 0.7% difference. The intraspecific variations among the P. alluriensis sequences, uploaded from the nearby area of the type locality are 0.0 to 0.8%. Despite minor variations in morphological traits such as snout tubercles, anal fin black bar, and inter-orbital space, molecular analysis revealed no significant genetic differentiation among these species. These morphological variations are likely a result of habitat influences. Considering the overlapping morphological features supported by ML tree and ASAP analysis, P. odishaensis, P. alluriensis, and P. swaini (described from the Eastern Ghats) are suggested to be synonymous. As P. odishaensis was the first species described, the other two should be regarded as junior synonyms of P. odishaensis
Analyzing population dynamics and growth patterns of Cyprinus carpio and Carassius carassius in Anchar Lake, Kashmir
Full text linkThe present study examines the population dynamics of Cyprinus carpio (common carp) and Carassius carassius (crucian carp) in Anchar Lake, Kashmir, through the analysis of length- weight relationships (LWR), growth patterns, mortality rates, exploitation rates, and recruitment dynamics. The length-weight relationships for both species exhibited negative allometric growth, with C. carpio showing a regression equation of log W = 2.80 log L – 1.56 and C. carassius showing log W = 1.52 log L + 0.01. Growth parameters were estimated using the von Bertalanffy growth function (VBGF) yielding asymptotic lengths (L∞) of 31.60 cm for C. carpio and 30.00 cm for C. carassius, with respective growth coefficients (K) of 0.44 year–1 and 0.38 year–1. The total mortality rates were 1.26 year–1 for C. carpio and 1.54 year–1 for C. carassius, with fishing mortality rates of 0.44 year–1 and 0.79 year–1 respectively, indicating that C. carpio is subject to moderate exploitation (E=0.35) while C. carassius is overexploited (E=0.51). Recruitment patterns for both species were highest in spring and early summer, with C. carpio showing optimal recruitment between April and May. Virtual population analysis (VPA) and yield-per-recruit analysis revealed that C. carpio is currently harvested sustainably, while C. carassius faces overfishing risks. The study highlights the need for adaptive management strategies, including stricter fishing regulations and seasonal closures, to ensure the long-term sustainability of these fish populations in Anchar Lake
Unveiling hydro-edaphic dynamics of the Manakudy Estuary: implications for ecosystem health
Full text linkThe present study investigated the seasonal variations of physicochemical and sediment parameters in the Manakudy Estuary, a critical tropical estuarine ecosystem in India. Key water quality variables encompassing basic physicochemical properties, oxygen dynamics, inorganic carbon, major ions, primary productivity, and nutrient regimes were analysed, as these collectively regulate estuarine biogeochemical processes and biological functioning. These parameters are essential as they collectively influence the chemical and biological environment of the estuary. Seasonal samples were collected from three selected sites across the estuary over a one-year period from March 2024 to February 2025, covering four seasons with triplicate sampling at each site. Descriptive statistics i.e., mean ± standard error (SE) were calculated based on replicate samples at each site and season to evaluate spatial and temporal variability. Two-way ANOVA revealed significant effects of season and site on several physicochemical and soil parameters (p<0.001), indicating pronounced spatio-temporal heterogeneity in the ecological conditions of the Manakudy Estuary. Such variability reflects shifts in nutrient availability, oxygen balance, and productivity patterns, providing clear insights into the ecological condition and ecosystem health of the Manakudy Estuary and its vulnerability to environmental stressors
Evaluation of a government-funded business incubation program in the fisheries sector in Indonesia
Full text linkGovernment-funded business incubation programs have been increasingly implemented to support micro and small enterprises (MSEs) in Indonesia’s fisheries sector; however, their effectiveness is not well understood. Prior studies largely relied on administrative data and manager perspectives, giving limited attention to beneficiary experiences. This study evaluated the effectiveness of a government-funded incubation program targeting fishery processing and marketing MSEs in Indonesia from the viewpoint of incubator tenants. Using importance-performance analysis (IPA), the research examined ten essential program attributes across 47 MSEs that participated in the program between 2018 and 2022. Data were collected through structured questionnaires measuring both perceived importance and actual performance of program services. Statistical analyses including reliability tests, validity tests, and paired t-tests revealed significant gaps between importance and performance for all attributes (p < 0.05). The IPA matrix placed five attributes in the “Keep Up the Good Work” quadrant (processing technique training, good manufacturing practice/sanitation standard operating procedures training, laboratory testing support, design and packaging support, and promotion materials development), one critical attribute requiring immediate attention in the "Concentrate Here" quadrant (market expansion assistance), and four attributes in the "Low Priority" quadrant (quality certificate assistance, license and permit facilitation, business management training, and financing and investment support). The findings indicated that while the program performed well in technical and operational support, market expansion services required substantial improvement. This study contributed to the limited empirical literature on government-funded fishery incubation programs in developing countries and offered actionable recommendations aligned with stakeholder priorities
Feasibility of cage culture of Asian seabass in coastal rivers of Bangladesh
Full text linkDespite its aquaculture potential, Asian seabass (Lates calcarifer) has not yet been adopted for cage culture in Bangladesh. This pilot study aimed to assess the feasibility of cage culture of this species in coastal rivers of Bangladesh. A total of six cages (18 m3 each) were installed in a coastal river and each was stocked with 50 fish (7.70 ± 0.18 g). Three feeding treatments were applied: 100% live feed (live and/or trashed juvenile tilapia) (T1); 50% live feed with 50% formulated feed (T2); and 100% formulated feed (T3). The experimental fish were reared for 12 weeks and fed at 8% of their body weight during the initial 3 weeks and at 6% during the later weeks. Fish refused formulated feed. Survival in T3 (64%) was significantly lower compared to that in T1 (88%) or T2 (82%) but did not differ between T1 and T2. Mean specific growth rates (SGR) were 1.66, 1.12, and 0.90 % d–1; daily growth rates (DGR) were 2.20, 0.74, and 0.44 g, and weight gain (WG) values were 182.50, 61.10, and 36.50 g in T1, T2, and T3, respectively. SGR values significantly differed among the treatments. DGR and WG values in T1 were significantly higher than that in T2 or T3 but did not differ between T2 and T3. Results indicate that cage culture of Asian seabass in Bangladesh requires live and/or trash fish as feed, or else advances in domestication and artificial feed development
Impact of high intensity ultrasound on the quality and preservation period of blue shrimp (Litopenaeus stylirostris) muscle
Full text linkDue to the limited shelf life of aquatic products, the use of advanced technologies to extend their freshness has become more popular recently. This study aimed to assess the impact of high-intensity ultrasound (HIU) on the quality of blue shrimp (Litopenaeus stylirostris) tails during 20 days of ice storage. Shrimp samples were treated at 70% amplitude for 0 (C), 30 (T1), 60 (T2), and 90 (T3) minutes. Key quality parameters were analyzed every 5-day. The initial total bacterial count (TBC) was 2.02 log CFU g–1, increasing to 6.09 (C), 5.32 (T1), 5.01 (T2), and 5.34 (T3) at the end of storage, with the control samples exceeding the acceptability limit. In terms of color, the initial L* value was 52.96, increasing to 62.96, 57.69, 57.94, and 57.78 for C, T1, T2, and T3, respectively. No significant differences were observed among treatments in pH (ranging from 7.22 to 8.33), shear force (from 15.40 to 18.50 N), water-holding capacity (from 93.02 to 98.23%), TVB-N (from 24.11 to 31.61 mg 100g–1), or non-protein nitrogen (from 0.78 to 0.48%). Likewise, SDS-PAGE profiles showed no visible protein degradation. These results indicate that HIU, particularly at 60 minutes, can extend shelf life by delaying microbial growth and preserving color, without adversely affecting the physicochemical or structural properties of the muscle
Evaluation of silkworm pupa meal on growth, body indices, digestive enzymes and histopathology of Cirrhinus mrigala fingerlings
Full text linkThe world's growing population needs food, and aquaculture; a fast growing food producing sector, provides it. Fish meal (FM) is a major feed source in the aquaculture industry, but its low profitability and scarcity have prompted a quest for high-protein substitutes. Because silkworm pupa meal is inexpensive and has a high protein (50–60%) concentration, it was utilized as a substitute for fish feed. The goal of the current study was to determine the ideal proportion of silkworm pupa meal (SPM) to substitute for FM while creating an affordable feed for Cirrhinus mrigala fingerlings (average total length: 6 cm; average weight: 8 g). The fingerlings were fed six test diets (0, 20, 40, 60, 80, and 100%) at a rate of 4% of their live wet body weight twice a day. Diets contained chromium oxide as an inert marker. The feeding trial lasted for ninety days. The fingerlings' weight was measured every 14 days to calculate growth metrics (weight gain percentage, FCR, and SGR). Following the conclusion of the trial, intestinal histology, digestive enzyme function, and body indices were examined. Highest growth rate (WG%: 333%, SGR: 1.64, FCR: 1.26, CF: 1.50) and best body indices (hepatosomatic index: 1.95, viscerosomatic index: 6.43) values were observed at 40% replacement of FM. Intestinal histological analysis and digestive enzyme activity demonstrated that SPM can be readily substituted up to 40% without affecting the general performance of C. mrigala fingerlings and aid in creating an economical and environmentally friendly diet