Photoperiod and Temperature Control in the Regulation of Reproduction in the Female Catfish Heteropneustes fossilis

The annual reproductive cycle of the catfish Heteropneustes fossilis is divided into the preparatory period (February–April), prespawning period (May–June), spawning period (July–August), and postspawning period (September–January). Ovarian recrudescence, which normally occurs during the prespawning period, can be advanced by photothermal manipulations. During the postspawning and preparatory periods, the tempo of ovarian recrudescence is much faster at 30 C than at other temperatures (ambient, 25 or 34 C) regardless of photoperiod (14L + 10D, 12L + 12D, or 9L + 15D).Warm temperature (30 C) postpones the postspawning ovarian regression only up to the first week of October regardless of photoperiod. The ovarian cycle is regulated by a circannual rhythm which can be activated 5 mo earlier, but its activity cannot be prolonged beyond October by photoperiodic and temperature manipulations.Interruption of the night of a short day (6L + 18D) treatment by 1 h of light between 0000 and 0100 induces ovarian recrud...