Production of all male population of Indian catfish Heteropneustes fossilis (Bloch) by immersion and oral treatment of 17α-methyltestosterone

Abstract

Male dominated population of Indian catfish, Heteropneustes fossilis (Bloch) was produced through immersion and oral treatments with 17a-methyltestosterone (17a-MT). Two approaches were tested in immersion treatment. A group of fertilized eggs was exposed to a short duration treatment of 3 h with 17a-MT at 0, 50, 100, 150 and 200 µgl-1 and another group to a long duration treatment of 10 days at the same doses. A separate group of 3 days old hatchlings were fed with the hormone at 0, 5, 10, 15 and 20 mg kg-1 feed over a period of 28 days. Gonadal histology of the fishes 4 months post-treatment revealed significant (p 0.05) difference between 50 and 100 µg l-1 concentrations in both short term and long term immersion treatments.