Effect of marigold oleoresin on growth, survival and pigmentation in orange chromide, Etroplus maculatus (Bloch, 1795)

The study was conducted to evaluate the effect of marigold oleoresin on growth, survival and total carotenoid content in muscle tissue of Etroplus maculatus. Fish with size group ranging from 0.60 g to 0.62 g were used for the study. The study was carried out in triplicate groups for a period of 45 days. Fishes were stocked at the rate of 15 per tank. Three test diets namely T1, T2 and T3 with 30% protein level were formulated. Diet T1 had 60 ppm, T2 had 120 ppm and T3 had 180 ppm marigold oleoresin, and diet without marigold oleoresin supplementation served as control (T0). There was no significant effect in survival rate and feed conversion ratio of the fish (p>0.05). However, 60 ppm marigold oleoresin fed fishes showed increased weight of 1.04±0.08 g, lower feed conversion ratio of 1.53±0.05 and higher survival rate (82.14%) than the other treatment groups. The fishes fed with 60 ppm marigold oleoresin incorporated diet showed significantly higher specific growth rate of 1.36±0.21%, relative growth rate of 69.10±3.4% and the absolute growth rate of 0.42±0.02 g. The body colouration and total carotenoid concentration of muscle tissue (4.62±0.02µg g-1) was significantly higher in fish fed with 60 ppm marigold oleoresin diet. Among the tested doses, 60 ppm marigold oleoresin showed better results than 120 ppm and 180 ppm marigold oleoresin inclusion in the fish diet.