Short‐ and long‐term effects of imposition of total darkness on the annual ovarian cycle of the catfish,Heteropneustes Fossilis(Bloch)∗∗

Two experiments were performed to investigate the short‐ and long‐term effects of imposition of total darkness on the reproductive cycle of the catfish. In the short‐term experiment, ovarian recrudescence occurred even in the absence of photoperiod but the magnitude of ovarian enlargement was significantly reduced. In the long‐term experiment also, ovarian recrudescence was noticed but the circannual rhythm was out of phase. The significance of these findings is discussed with reference to the annual reproductive cycle of the catfish.