The effect of dietary 17α‐methyltestosterone administration on secondary sex coloration in adult female Rosy Barbs and Dwarf Gouramis

Abstract

AbstractSexual phenotype is highly plastic in teleosts and controlled by a variety of species‐dependent factors. In aquaculture, hormone manipulations applied at different life stages are used to control sex ratios and exploit desirable traits such as ornate coloration in male ornamental species. This study investigated the effects of dietary 17α‐methyltestosterone (MT) administration on adult female Rosy Barbs Pethia conchonius and Dwarf Gourami Trichogaster lalius and Dwarf Gouramis. A panel of judges evaluated male secondary sex coloration weekly during and after prolonged MT feeding. Growth parameters, survival, and gonadosomatic index (GSI) were assessed at the end of the feeding regime. In both species, none of the MT diet concentrations affected survival, and all resulted in coloration changes, highlighting both the efficacy and safety of MT administration. In Dwarf Gouramis, MT diets caused pronounced color changes and reduced their GSIs at all dietary concentrations. In Rosy Barbs, MT diets induced the expression of male coloration but generally did not reach the color intensity of naturally occurring males and did not result in differences in GSIs. This study suggests that postdifferentiation androgenic treatment may be a viable option to induce secondary male sex coloration in ornamental species.