Harnessing freshwater snails to enhance water quality and sustainability in integrated multi-trophic prawn farming systems, Bangladesh

Bangladesh’s climate is favourable for giant freshwater prawn (Macrobrachium rosenbergii) farming, but conventional practices contribute to high greenhouse gas (GHG) emissions, threatening aquaculture sustainability. Integrated multi-trophic aquaculture (IMTA) offers a promising approach to mitigate GHG by incorporating species that extract excess organic matter from farms. Molluscs, particularly snails, have been suggested as potential extractive species. This study aimed to identify suitable local snail species for IMTA in the southwestern Khulna district across three salinity zones (low, medium, moderately high) during the monsoon (July–October). Sampling covered three waterbody types: aquaculture, non-aquaculture and open waterbodies. Year-round perceptions-based data were obtained through focus group discussions (FGDs), while direct quadrat sampling provided monsoon-season field observations data, identifying nine and seven mollusc species, respectively. Bellamya bengalensis was most abundant in late monsoon within non-aquaculture waterbodies (39.56 ± 12.74 individuals/m²), whereas Pila globosa peaked in mid-monsoon (10.22 ± 3.41 individuals/m²). Snail abundance was highest in undisturbed, vegetated non-aquaculture waterbodies. Distribution patterns were influenced by salinity and water quality parameters. Both B. bengalensis and P. globosa show potential for IMTA for their availability and potential use in feed, with B. bengalensis particularly suited because of its filter-feeding behaviour, adaptability and rapid reproduction.