Shifts in fish assemblages in paddy ecosystem: a study of space and time

Paddy fields, as seasonal and disturbed wetlands, offer temporary habitats that support freshwater fish. This study investigates changes in fish assemblages across different stages of paddy planting and habitats over two planting seasons. Fish were collected from the main river, concrete canals, earth ditches, and storm drains at three stages: vegetative, reproductive, and ripening. A total of 26 species from 14 families were recorded, with species richness increasing towards the end of the seasons. Average taxonomic distinctness (AvTD) analysis revealed minimal variation among stages and habitats. Non-metric multidimensional scaling (nMDS) analyses showed distinct groupings of fish assemblages by stage and habitat. ANOSIM results confirmed significant differences among the vegetative, reproductive, and ripening stages, with habitats exhibiting even greater dissimilarity. SIMPER analysis identified species such as Anabas testudineus and Clarias macrocephalus (blackfish) and Barbodes binotatus, and Esomus metallicus (whitefish) as some of the key contributors to community similarity across stages and habitats. These findings highlight the ecological significance of paddy fields as temporary wetland ecosystems in supporting fish diversity and underscore the need for maintaining habitat connectivity within agroecosystems.