Study of Reproductive Physiology of Red Tilapia (Oreochromis sp.) after Tyroxine Treatment and Rearing at various Salinity Media

Abstract

Tyroxine or tetrayodotyronine (T4) hormone and salinity are the two most important variables for osmoregulation, metabolism, and reproduction of fish. The research was conducted to evaluate reproductive physiology of red tilapia under different media salinity and tyroxine doses. Thyroxine was administrated to the fish by injection four times every two week. The research consist of nine treatments and three replications with combination between tyroxine and media salinity were (A) Thyroxine (T4) 0 ng /g body weigh (BW), salinity 0 ppt; (B) 0,10; (C) 0,20; (D) 50, 0; (E) 50, 10; (F) 50, 20; (G) 100, 0; (H) 100, 10; and (I) 100, 20. The result showed that tyroxine administration could increase osmotic gradient, fat and protein retention. Thyroxine administration also have influenced to gonadal development including gonado somatic index, hepato somatic index and fecundity. The combination between tyroxine 100 ng/g BW and media salinity 10 ppt and gave the best for reproduction performance of red tilapia.