Effect of Fluoxymesterone Fish Feed Granule on Sex Reversal of the Hybrid, Thai Red Tilapia (Oreochromis niloticus Linn. x Oreochromis mossambicus Linn.)

Abstract

Effects of an androgen, fluoxymesterone on sex reversal and gonadal development of Thai Red Tilapia, the hybrid of Oreochromis niloticus x O. mossambicus were investigated. Four days old fry were fed with feeds containing three different concentrations of fluoxymesterone (40, 60 and 80 mg•kg-1 fish feed) for 21 days. Fry fed with 40 mg•kg-1 fish feed of fluoxymesterone showed the highest percentage of males reversal of 96.10% (p < 0.05). Higher dose of fluoxymesterone at 60 and 80 mg•kg-1 fish feed increased the percentage of intersex and sterile fish. Higher growth rate of fish treated with fluoxymesterone in comparison to the control groups was observed. However, no significant differences in survival rate between the fluoxymesterone treated and the control groups were seen. No residual fluoxymesterone in 5 months old fish were detected. The morphological and histological studies demonstrated that fluoxymesterone can be used to control the gonadal development and phenotypic sex of the Thai Red Tilapia. This study suggested that fluoxymesterone can be used efficiently for sex re- versal in the hybrid, Thai Red Tilapia.