Effects of 17 α-methyl testosterone on the secondary sex characteristics in the Scat (Scatophagus argus)

17 α-methyl testosterone is an androgenic hormone and is involved in the sexual cycle and is used in increasing growth and masculinization. In this study, effects of different doses of hormone (300, 400 and 1000 mg/kg) with a control treatment (0 mg/kg) on color measurement on scat (Scatophagus argus) were studied. Color was measured by color and appearance measurement system. The results indicated an increase in red pigment in fish specimens. Dosage of hormone was increased to watch shiny red color after about 45 days. Our results indicated a strong relationship between physiological characteristics of fish and color and secondary sex characteristics.Tinge in lateral region of the body in fish specimens with doses of 0, 300 and 400 was not significantly different (P>0/05), while dose of 1000 mg kg diet was significantly different (P<0/05). And the most colored fish specimens were observed with dose of 1000. This result showed the tendency to increase red tinge with an increase in dose. While all doses studied, no significant differences were seen in the tinge of the tail fin and trunk (P<0/05). However tinge factor in the tail region fin of fish, was significantly different (P<0/05) and decreased toward red tinge.