Molluscs are the most important resources among all the seafood items in South-East Asian countries. However, very little information available on nutritional value of molluscs in these regions. In this study, we evaluated the 7 economically important species of molluscs in terms of proximate composition, amino acids profile, fatty acids profile, cholesterol and heavy metal contents in the bivalves (mussels, oysters, clams and cockles) and univalve (snail) collected from freshwater and marine environments of Bangladesh. The results of the proximate analyses revealed that significantly higher amount of crude protein contents were present in marine water oysters, clams and cockles (59.3 ± 0.3 to 75.4 ± 0.2%) than the freshwater mussels and snail (36.9 ± 0.4 to 49.6 ± 0.6%) on dry matter basis. However, carbohydrate contents were significantly higher in freshwater mussels and snail (30.2 ± 0.9 to 57.3 ± 0.2%) compared to the marine water bivalves (8.1 ± 0.4 to 20.2 ± 0.6%). Crude lipid contents were ranged from 2.5 ± 0.2 to 11.2 ± 0.1% and ash from 11.4 ± 0.1 to 16.8 ± 0.6% among the bivalves and snail species. The amino acid contents were comparatively higher in marine water bivalves than their freshwater counterparts. Saturated fatty acid contents were found to be higher in marine water bivalves than the freshwater mollusc species. The results also show that the omega-3 (eicosapentaenoic acid, EPA and docosahexaenoic acid, DHA) fatty acids were comparatively higher in oysters, clams and cockles in marine water than those in freshwater mussels and snail. However, omega-6 fatty acids like linoleic acid (LA), α- linolenic acid (ALA) and arachidonic acid (ARA) were higher in freshwater mussels and snail than in the marine bivalves. The n-3/n-6 ratio were significantly higher in oysters and cockle species than the other groups of bivalves and snail. The index of atherogenicity and index of thrombogenicity of the mollusc species ranged from 0.74 ± 0.1 to 1.74 ± 0.2 and 0.5 ± 0.1 to 2.6 ± 0.2, respectively. The results show that marine water bivalves contained higher amount of potassium, sodium, iron, chlorine especially oyster species contained significantly higher iodine than the freshwater bivalves and snail. However, freshwater mussels and snail showed significantly higher amount of zinc contents than the marine bivalves. The heavy metal contents such as arsenic, chromium and mercury were absent or present in very tiny amounts among the mollusc species. Significantly higher amount of cholesterol was present in marine bivalves and freshwater snail species than the freshwater mussels. Overall, the results indicate that marine bivalves can be good sources of high quality protein and lipid especially EPA and DHA. On the other hand, freshwater mussels and snails also could be good sources of protein, LA and ARA but scarcity of EPA and DHA.

An integrated multivariate approach was applied to gain a deeper understanding of the feeding biology of hilsa shad, Tenualosa ilisha, collected from six different aquatic habitats across Bangladesh. This approach involved linking climatic factors, ecological factors, plankton abundance in water, reproductive traits, and plankton ingestion data. Climatic data were obtained from the National Oceanic and Atmospheric Administration (NOAA) and Climate Data Online (CDO) databases on a monthly basis. Water quality parameters were observed on-site at various sampling sites. Plankton data from water bodies and hilsa guts were collected monthly from the study areas and analyzed in the laboratory. The results obtained were averaged for each month. The correlation tests, multivariate approaches, cluster analyses, and regression analyses revealed that the gonadosomatic index was primarily influenced by climatic factors, the abundance of ingested gut plankton, and heir compositions. The analysis of selectivity indices confirmed that plankton preferentially ingested selective taxa. Thirteen plankton groups were identified in the water column of six different hilsa habitats. The dominant phytoplankton groups were Bacillariophyceae (34–53%), Chlorophyceae (31–50%), Cyanophyceae (4–8%), and Euglenophyceae (1–3%). Additionally, Copepoda, Rotifera, and Cladocera were the most numerous zooplankton groups. Hilsa shad primarily consumed Bacillariophyceae (38–57%), Chlorophyceae (35–53%), and Cyanophyceae (4–6%). However, they also exhibited selective ingestion of higher quantities of Bacillariophyceae and Chlorophyceae to fulfill specific and unique metabolic needs. Cluster analysis revealed the variability of phytoplankton and zooplankton abundance in water and gut in relation to diverse locations. Combining all the datasets, a principal component analysis (PCA) was applied. The first two principal components explained more than 54% of the variability. The first component explained the association between the gonadosomatic index and eco-climatic factors, while the second component extracted the cluster of ingested gut plankton in relation to salinity and pH. Pearson’s correlations and linear regression analyses showed that the number of gut plankton had a positive influence on the gonadosomatic index (GSI). Finally, the outcomes from these extensive datasets have provided a better understanding of the selective feeding behavior and the influence of feeding biology on the gonadal maturation of T. ilisha. This understanding is likely to be useful for maintaining and improving the growth and productivity of the existing production systems for this transboundary species.

Long-term frozen storage deteriorates the quality of hilsa fish (Tenualosa ilisha), famous for its delicious taste and flavors. Vacuum packaging may retain the flavor and quality of hilsa fish. To this end, biochemical and microbiological analyses were used to assess the quality of hilsa fishes under whole without pack, whole with vacuum pack, dressed without pack, and dressed with vacuum pack, at a monthly interval during a year of frozen storage at −18 °C. There were no significant differences (p > 0.05) in the values of pH, free fatty acids (FFA), total volatile base nitrogen (TVB-N), and aerobic plate count (APC) among the treatments, and the values remained within the acceptable limit during the storage period. However, thiobarbituric acid reactive substances (TBARS) were significantly (p < 0.05) lower in samples under vacuum (whole and dressed) compared to samples without pack. TBARS values did not cross the acceptable limit for vacuum pack samples in nearly the entire storage period but were exceeded for samples without pack within the first month. It is assumed that the vacuum packaging reduced the secondary oxidation of fatty fish like hilsa during the frozen storage, which can ensure a year-round supply of quality hilsa fish without altering its distinctive taste and flavor.

The studied area is the single largest fishery in Bangladesh. The present work was conducted at two points of the Padma River (Sureshwar and Tarabunia) from July 2019 to June 2021 to monitor the efficiency of the 5^th Hilsa sanctuary. Proportion of spent rate, length frequency, larvae and Jatka abundance, CPUE of larvae, the length-weight relationship of Jatka, plankton composition, and physico-chemical parameters of water were assessed and found adequate in the Hilsa sanctuary.

This study was conducted in farmer’s ponds within the northern region of Bangladesh to observe the growth and yield of Shing, Heteropneustes fossilis under a polyculture system. The highest total production of fish registered among the treatments in pattern-1 was 6,331 kg ha ⁻¹ with a benefit-cost ratio of 1.52. The best combinations were chosen for multi-location testing (MLT) to verify the previous results. After five months of multi-location testing of the selected combinations with Shing as the main species, the significantly (P < 0.05) highest production of Shing (5,828 kg ha ⁻¹ ), total production of fishes (7,352 kg ha ⁻¹ ) and benefit-cost ratio (1.73) were found.