Effects of 17 Alpha-Methyltestosterone on Growth, Survival and Sex Reversal of Thai Walking Catfish, Clarias macrocephalus

Abstract

Fry of Clarias macrocephalus were fed at first feeding with water fleas (Moina sp.) immersed for 20 minutes in 200 ppm or 400 ppm MT for 15 days. The groups fed water flea (200 ppm MT) were fed a diet containing 30 mg MT and the groups fed water flea (400 ppm MT) were fed 60 mg MT, for the additional 15 or 45 days. Results indicated that administration of MT did not affect growth (P>0.05) at 33 days but retarded growth at 63 days of all treated groups. Growth of treated groups was increasingly suppressed with increased dose and duration of treatment. Administration of MT lowered survival rate at 33 days (P<0.05). Survival from day 33-63 was unaffected by the hormone application. Ovotestes were found in the groups treated with 30 and 60 mg MT for 60 days. In general, sex reversal to maleness was not accomplished, and with increasing dose and duration there appeared to be paradoxical feminization. Alternatively, MT may have prevented gonads of genetic males from differentiation or caused the formation of ovotestes in genetic females.