Temperature dependent action of estrogen in Singi fish (Heteropneustes fossilis Bloch)

The responsiveness of the non-vitellogenic Singi fish to exogenous estrogen has been studied at different environmental temperatures. Estrogen was found to be effective in fish kept at 25 degree C and 30 degree C, as evidenced from the increase in hepatosomatic index (HSI), plasma protein and liver protein and RNA contents, and a fall in liver glycogen content after injections of estradiol dipropionate (1 microgram/g) for 7 consecutive days. Such estrogen-induced changes were not observed in the fish kept at 15 degree C, indicating the ineffectiveness of this sex steroid at this lower temperature.