Growth response of juvenile clownfish Amphiprion sebae Bleeker, 1853 fed with graded levels of dietary protein

Abstract

Clown fishes are the most popular marine ornamental species owing to their unique behaviour and symbiotic association with sea anemones. Captive propagation of these fishes is relatively easy; however, the lack of suitable diets influences their survival, growth and colouration. In this study, growth response of juvenile sebae clownfish Amphiprion sebae Bleeker, 1853 was evaluated through a feeding trial. Six iso-caloric experimental diets with graded dietary protein levels of 33.06 (D33), 36.54 (D36), 39.19 (D39), 41.88 (D42), 45.17 (D45) and 47.94% (D48) of dry matter were prepared. Lipid content of approximately 6% was maintained for all dietary treatments. The study was conducted for nine weeks in triplicate to evaluate survival, growth and feed utilisation. Fishes fed with diet D36 did not present any mortality; those fed diets D39, D45 and D48 had a lower survival with 86.7%, without significant differences among the treatments. However, weight gain, specific growth rate (SGR) and feed conversion efficiencies showed a significant difference among the treatments (p<0.05). Weight gain and SGR of sebae clownfish increased gradually among tested diets and peaked at D45 (697.28 mg and 3.84). A sharp decline in weight gain and SGR (486 mg and 3.39) was observed with the replicates fed with D48. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were superior with diets D42 (1.40 and 1.71) and D45 (1.60 and 1.38). The results of the present study revealed higher growth when fed with dietary protein level of 45%. The second-order polynomial regression on SGR and weight gain suggested an optimal dietary inclusion at 44.9 - 46.2%. Based on these results, it can be inferred that juvenile sebae clownfish has a higher dietary protein requirement of about 45%. However, the study also suggested the efficacy of diets having 36% protein and 6% lipid for healthy aquarium upkeep of sebae clownfish. These findings will be beneficial for the commercial propagation and maintenance of clownfishes.

Keywords: Anemone fish, Dietary protein requirement, Feed efficiency, Growth, Marine ornamental fish