Debasish Saha

Microplastics (MPs) are widespread aquatic pollutants that can accumulate in fish, posing potential risks to food safety and human health. This study investigated MPs in ready-to-use fish powders (RUFPs) from Bangladesh and evaluated their reduction through primary processing. Three powder types—whole fish powder (WFP), eviscerated fish powder (EFP), and fish muscle powder (FMP), prepared from five small fish species: Anchovy (Coilia sp.), Fringescale sardine (Sardinella fimbriata), Ganges river sprat (Corica soborna), Indian river shad (Gudusia chapra), and Pool barb (Puntius sophore). A total of 157 MPs were detected in 13 RUFP samples, with concentrations of 0.4–3.4 (1.21 ± 0.77) MPs g-1 dry weight. Among WFPs, Fringescale sardine had the highest concentration, followed by Indian river shad, Pool barb, Anchovy, and Ganges river sprat. MPs decreased from WFP to EFP to FMP (0.8–2.6, 0.6–2.2, and 0.6–1.4 MPs g-1, respectively). On an extrapolated wet-weight basis, processing reduced MP loads by 46–52% after evisceration and 54–77% after muscle isolation relative to whole fish. Most MPs were fibers, blue in color, and 20–150 µm in size. ATR-FTIR identified synthetic polymers and cellulose derivatives. Overall, processing substantially reduced MP loads, indicating its potential to improve the safety of fish-based products.

Nappi , a fermented fish product having culinary significance in ethnic communities, often experiences a decline in quality due to improper storage conditions, leading to a reduced shelf life. Therefore, sorbitol, a polyhydric alcohol, possesses antioxidant properties, and its dual role as a humectant and bulking agent, which underscores its value as an organic food preservative, was applied to increase the shelf life of Nappi . Different amounts of sorbitol ST0‐0, ST1‐1, ST2‐2, ST3‐2.5, and ST4‐3 g/100 g Nappi were incorporated, and their effects on physiochemical, microbiological, and oxidative stability were inspected for 90 days at room temperature. During the observation period, pH and thiobarbituric acid reactive substance (TBARS) of the sorbitol‐treated Nappi (STN) were significantly lower in comparison to control ( p < 0.05). STN reduced the TBARS values by ~30%–38% compared to the control samples. Additionally, STN showed 7.84%–32% lower total plate count (TPC) than control ( p < 0.05) on the 45 ^th day of storage. Organoleptic properties demonstrated better sensory quality in STN in terms of color, texture, odor, and appearance. Hence, analyzing the present study, it can be concluded that Nappi treated with sorbitol extends the shelf life, and specifically with a 3 g/100 g sorbitol addition, it upholds the best attributes for 90 days without having an adverse effect on its sensory parameters, highlighting its efficacy for Nappi preservation.

This study optimizes hormonal induction techniques and water quality parameters to improve reproductive success in Grass Carp (Ctenopharyngodon idella). Conducted over a year at Bismillah Fish Seed Production Center, Bangladesh, key reproductive indicators including gonadosomatic index (GSI) and hepatosomatic index (HSI) were monitored. Peak values were observed in March, with females showing a GSI of 21.48±2.69% and an HSI of 8.03±1.83%, and males at 1.37±0.38% (GSI) and 4.68±0.23% (HSI). Six hormonal treatments (CPG, HCG, Ovupin, and combinations) were tested. Ovulation rates ranged from 47% to 95%, with Ovupin inducing the shortest ovulation period (5.48 hours) and HCG the longest (7.18 hours). Fertilization rates varied from 65.74% to 93.48%, with CPG (T1) achieving the highest fertilization (93.48±5.83%) and hatching rate (89.36±7.26%). Larval survival rates after 48 hours were highest with CPG (73.9±3.79%) and lowest with HCG (32.5±2.14%). Optimal water quality parameters contributed to successful breeding. The study concludes that CPG and Ovupin + CPG are the most effective protocols for enhancing Grass Carp reproduction.

The yellowtail catfish (Pangasius pangasius) population in Bangladesh is facing imminent threats that led to endangered status. We used conventional scientific knowledge (CSK) and local ecological knowledge (LEK) of fishers (n = 155) to identify nursery grounds and spawning seasons of yellowtail catfish in the Meghna river estuary. Nineteen nursery grounds were pinpointed using fishers' LEK (confluence/influent zone, current, depth, catch data, and turbidity) and later validated by CPUE data. The peak spawning season was identified in July–September based on GSI (gonadosomatic index) and LEK (58.06% of fishers identified the spawning season). Fecundity (810,980 ± 455,679) and condition factor (0.94–1.52) were quantified with CSK. Using CSK and LEK to delineate nursery grounds and spawning season underscores the value of LEK as a tool for fish population management that deserves policy recommendation and wider application.

The current study examined the length-weight relationships (LWRs), length-length relationships (LLRs), and condition factor (K) of four threatened riverine catfish species (Pangasius pangasius, Rita rita, Sperata aor, and Bagarius bagarius) sampled from the Meghna River Estuary (MRE), Bangladesh. A total of 578 individuals were collected from contracted fishermen between January and October 2022. The length and weight of each species exhibited a highly positive correlation. The regression coefficient was 2.24 for P. pangasius, 2.90 for R. rita, 2.91 for S. aor, and 3.25 for B. bagarius. Furthermore, all species demonstrated a highly positive correlation between total length and standard length (r>0.90). The calculated condition factor (K) values were 0.87 for P. pangasius, 1.18 for R. rita, 0.66 for S. aor, and 0.99 for B. bagarius indicating variations among the species. This study provides the first comprehensive documentation of all four major catfish species found in the MRE.