Paradoxes in exogenous androgen treatments of bluegill

Three experiments were conducted to investigate the effect of oral administration of trenbolone acetate and 17a-methyltestosterone on sex determination in 28-day-old bluegill, Lepomis macrochirus Rafinesque, fry. Multiple androgen doses and various treatment durations were tested. All treatments produced fewer males and females than did the control group (P < 0.01). All concentrations of both androgens produced a high proportion of intersex fish (38–81%). The number of males and females declined with the increase in androgen dose or treatment duration. Sterile fish were found in treatments with a higher dose rate or a longer treatment period. The predominance of intersex fish and reductions of both males and females in the androgen treatments suggest that gonadal development of both genotypic male and female fish were being altered by the hormone treatment.