Effect of Different Kinds of Live Feed on Thyroid Structure of Marine Fish Larvae Coral Trout Plectropomus leopardus (Lacepede, 1802)

Coral trout is a highly economical grouper species and a very prospective marine fish culture in Indonesia. Hormonal is an important physiological factor of marine fish larvae including thyroid hormone which plays an important role during the larval stage. On the other hand, the appropriate of zooplankton as live feed is the key success of larvae rearing in aquaculture. In order to support the aquaculture success, it is important to understand the thyroid structure, as a basic knowledge of thyroid studies. The effects of different kinds of live feed on thyroid structure of coral trout larvae was studied using three feeding schemes: copepods (A), copepods + rotifers (B) and rotifers (C). Histological observation of 15, 20, 25 and 30 days old larvae samples was done by Haematoxylin-Eosin staining. The observation included the number of thyroid follicles, also the length and width of thyroid follicles. The results indicated that larvae A had greater in number, bigger in size and more active thyroid follicles than larvae C. Based on this study, the different kinds of live feed, i.e. copepods and rotifers, resulted in various effects upon thyroid structure of coral trout larvae. Larvae were fed copepods had greater in a number of thyroid follicles, bigger in size and showed more active thyroid follicles compared to larvae were fed rotifers.