Dietary carotenoprotien extracted from shrimp shell waste augments growth, feed utilization, physio-metabolic responses and colouration in Oscar, Astronotus ocellatus (Agassiz, 1831)

Abstract Carotenoprotein, a complex of carotenoids and protein, extracted from shrimp shell waste can be an effective source of carotenoid as well as antioxidant in fish diets. In the present study, the nutritional potential of carotenoprotein extracted from shell wastes of Parapeneopsis stylifera on growth, physiometabolic changes and coloration in high-value ornamental fish, oscar (Astronotus ocellatus) was assessed in a 120 days feeding trial. Four iso‑nitrogenous (30–31% CP) and isolipidic (11.34–11.55% CL) diets were formulated with graded levels of carotenoprotein inclusion like 0%, 5%, 10% and 15% and designated as Control, T1, T2 and T3 respectively. At the end of the feeding trial, growth indices such as final body weight, weight gain, and specific growth rate indicated that fish fed with 10 and 15% levels of carotenoprotein incorporated diet showed higher growth compared to control and T1. Oxidative stress enzymes like SOD and Catalase were lower in 15% and 10% carotenoprotein incorporated diets respectively in both gills and liver. Stress indicators like serum glucose and cortisol activity were found to be higher in control than in diets with 10% (T2) as well as 15% (T3), suggesting the stress-reducing ability of the carotenoprotein in fish feed. Relatively higher respiratory burst activity in fishes of T3 group indicated higher immunity status of the fish. Quantitative colour values in terms of redness, chroma in the fin region as well as carotenoid content in scale, skin and muscle of fish were higher in T2 (10% carotenoprotein incorporated diet) as compared to T3 (15% carotenoprotein incorporated diet). Overall, this study clearly showed that dietary incorporation of as little as 10% carotenoprotein is advisable to ornamental fish farmers for enhanced growth, colouration, as well as antioxidant activity in this popular high value ornamental fish for maximizing their profit.