Growth performance, carcass composition, and digestive enzyme activity of Labeo fimbriatus in tanks provided with feed and periphyton substrate in two orientations

ABSTRACT The effect of substrate orientation on the growth of Labeo fimbriatus in periphyton-based culture system was evaluated through an on-farm growth trial conducted for 90 days in 4x4x1.2 m soil-based, fertilized out-door cement tanks. The treatments consisted of triplicate tanks receiving no feed (NF), receiving feed (F), and those receiving sugarcane bagasse as periphyton substrates vertically suspended in the water column (SV) or applied directly to the tank bottom (SB). Bagasse used at 2 t/ha was hung vertically in SV tanks, while it was spread at the tank bottom in SB. Fish in F treatment tanks were fed daily with a 25% crude protein diet. No significant effect of periphyton substrate on growth performance and production of L. fimbriatus was observed when compared with the group receiving feed. Survival was not affected by the treatments. Production did not vary between the substrate orientations. Carcass of fish in F, SV, and SB had similar proximate composition. Activity of gut digestive enzymes was higher in treatments with substrate as compared to no substrate treatments.