Impact of silver barb (Barbades gonionotus Bleeker) on growth and survival of prawn (Macrobrachium rosenbergii) in polyculture system.

Impact of silver barb (Barbades gonionotus) on the growth and survival of prawn (Macrobrachium rosenbergii) were tested in a polyculture system. There were two treatments and three replication of each. Silver carp (Hypopthalmichthys molitrix), catla (Catla catla) and prawn (M. rosenbergii) were stocked at a stocking density of 10, 3 and 50/decimal, respectively in both treatments. Rohu (Labeo rohita) was stocked at a stocking density of 8/decimal in treatments T1 and silver barb was stocked at a rate of 20/decimal in treatment T2. The average growth and survival rate of silver carp and catla were higher with rohu (T1) than with silver barb (T2). However, differences were not statistically significant .The specific growth rate (SGR) of prawn was higher in T1(1.98%) than in T2(1.86%). The significantly higher (P<0.05) survival of (70.85%) was found in T1, where rohu stocked with prawn and the lower survival (61.05%) was obtained in T2, where silver barb was stocked. The yield of prawn in T1 (649.25 kg/ha) was significantly higher (P<0.05) than T2(456.95 kg/ha). This finding reveled that survival rate and yield of prawn was affected by silver barb and it has exerted an antagonistic effect on growth, survival and production of prawn. Total fish production was significantly higher (P<0.05) in T2(2718.9) than in T1 .(2021.14), because the production of silver