The present study was conducted to know about the effect of different concentrations of synthetic androgen 17- Methyl testosterone (MT) on histological changes in gonads of male Dwarf Gourami, Trichogaster laliaus (Hamilton, 1822). Fishes were fed with homogenous mixture of the hormone in ethyl alcohol in its feed for 90 days. On the basis of histological study, the hormonal actions on the testicular changes were distinguished on the basis of the spermatocytes present i.e. primary spermatocytes, secondary spermatocytes and spermatozoa. In lower doses (5 mg/Kg & 10 mg/Kg of feed), the concentrations of the gonadal materials were so closely placed that the identification of different stages was found very difficult up to 45 days. In the higher dose (15 mg/Kg of feed), the gonadal materials were found less concentrated which leads a negative impact on the gonads after 60 days of treatment.