Evaluation of dietary oleoresins on the enhancement of skin coloration and growth in the marine ornamental clown fish, Amphiprion ocellaris (Cuvier, 1830)

Abstract

A 60-day feeding trial was carried out to investigate the effects of dietary oleoresin inclusion on skin colour intensity, carotenoid content, growth performance and digestive enzyme activities of a high value marine ornamental clown fish, A. ocellaris. Experimental diets were formulated with natural oleoresin pigments namely, paprika, turmeric and chlorophyll, with dietary inclusion at the rate of 20 gkg−1 in the diets. Experimental units were set in triplicates with six numbers of fish in each tank and maintained in filtered sea water of 20‰ salinity in a recirculatory system. Clown fish with average initial weight of 150.6 ± 0.10 mg and initial length of 8 mm were fed five different diets viz., control/ basal diet (C), diets with inclusion at the rate of 20 gkg−1 each of paprika (PAP), turmeric (TUR) and chlorophyll (CHL) oleoresins and combination of oleoresins (COM) at the rate of 20 gkg−1. Skin colour intensity in terms of red and yellow hues and total carotenoid levels differed significantly (P < .05) and highest intensity was recorded in fishes fed the PAP, followed by the COM group. Fish fed with the diet containing COM showed significantly higher final body weight, specific growth rate, weight gain % and feed efficiency as compared to other treatments and was followed by the PAP group. The whole body carotenoid content was highest in COM and PAP groups. There were no significant differences (P > .05) with respect to feed efficiency, digestive enzyme activities, viscero somatic index, visceral length index, condition factor and whole body proximate composition among different treatments. These results suggested that the dietary pigments have a direct influence on the skin pigmentation in A. ocellaris without adverse effects on digestive functions and body condition. Colour imparted in fish skin due to paprika oleoresin was found to be superior.