Lamellidens and Wolffia canopy improves growth, feed utilization and welfare of Labeo rohita (Hamilton,1822) in integrated multi-trophic freshwater aquaculture system

Abstract A 90 days' trial on integrated multi-trophic aquaculture (IMTA) incorporating floating weed Wolffia globosa as inorganic extractive and a bivalve Lamellidens marginalis as organic extractive was conducted to assess the growth, survival, yield, water quality and welfare of Labeo rohita (Rohu) in an outdoor tank culture system. Twelve cement tanks (20 m3) were randomly allocated into four treatments (in triplicate) where L. rohita was used as fed species. The treatments were assigned as control (C) only rohu, T1: Rohu and partitioned Wolffia canopy, T2: Rohu, L. marginalis and T3: Rohu, Wolffia and L. marginalis. The stocking densities for rohu and L marginalis were 30,000 fingerlings ha−1 and 750 kg ha−1 while Wolffia was transplanted to cover 30% of the tank surface area, and fish to mussel biomass ratio maintained was 2:1. The fish were fed with a sinking pelleted feed (30% Crude Protein) at the rate of 4% body weight. It is observed that total biomass, survival, net fish yield (NFY) was significantly highest in T3 as compared to T1, control and T2. The total protein and lipid content of rohu (whole-body) differ significantly between the treatments. Among the welfare parameters, the nitroblue tetrazolium (NBT) activity was significantly higher in T1 and T3 while superoxide dismutase (SOD) was highest in T1. The catalase (CAT) activity lowest in T3 among all the treatment groups. The water quality parameters like NH4-N, NO3-N, PO4-P were significantly lower in T3 among all treatment groups. Higher water transparency was observed with no algal bloom in T3 and T1. The results suggest that co-culture of L. rohita with W. globosa and L. marginalis can improve water quality, welfare parameters, enhancing fish survival and productivity.