Multifarious Biomarker Approach Elucidate Stocking Density Mediated Stress, Modulates Growth Attributes in Cage Reared Rohu, Labeo Rohita (Hamilton)

Abstract

The present study was conducted for 240 days to evaluate the effects of stocking density based on growth attributes, digestive enzymes, muscular composition, biochemical and physiological responses of Labeo rohita fingerlings in tropical inland open water cages. L. rohita (30.35±1.08 g) were randomly distributed into three treatments, namely low stocking density, LSD (10 m− 3), medium stocking density, MSD (20 m− 3) and high stocking density, HSD (30 m− 3) in triplicates. Fish were fed twice daily with CIFRI CAGEGROW® floating feed (crude protein-28%, crude fat-4%). Fish growth and feed efficiency was higher (P<0.05) in LSD, however MSD registered higher yield. Amylase and protease activity reduced whereas lipase activity increased with increasing stocking density. Muscle crude protein and crude fat formed inverse correlation. The fillet quality deteriorated at higher stocking densities based on Muscle pH, drip loss and frozen leakage rate. The stress biomarkers level (glucose, cortisol, superoxide dismutase and catalase) increased in serum under crowding condition. Glutamate oxaloacetate transaminase and glutamate pyruvate transaminase in serum was significantly increased in HSD. Serum protein level decreased with increase in stocking densities. Body ionic imbalance (Na+, Cl− and K+) observed under crowding stress. Based on growth attributes and multiple biomarker responses, L. rohita @ 10 m− 3 found to be optimum density for inland open water cage culture.