Effects of blinding and/or total darkness on ovarian recrudescence or regression during the appropriate periods of the reproductive cycle of the catfish,Heteropneustes fossilis(Bloch)∗∗

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Abstract
Three experiments were performed wherein intact and blind catfish were subjected to various photoperiodic regimes during the preparatory, the prespawning and the spawning period to ascertain the role of eyes in the perception of photoperiodic stimulus. In the first experiment, conducted during the prespawning period, intact and blind catfish were subjected to laboratory photoperiod (12 hr/day) or total darkness. The results indicate that ovarian recrudescence occurs in spite of the absence of eyes and light. But the tempo of ovarian recrudescence is slower in the blind animals than in the sighted animals. The results of second experiment where intact and blind catfish were subjected to total darkness for 163 days during the preparatory period show that ovarian recrudescence takes place in all the groups regardless of the presence or absence of eyes and/or of light. The magnitude of ovarian enlargement was greater in the intact control and intact catfish exposed to total darkness than in the corresponding blind groups. In the third experiment conducted during the spawning period, decreasing photoperiod induced a more precipitous ovarian regression in the presence than in the absence of eyes. Eyes, though important receptors for photoperiodic perception, are not indispensable. The presence of a self‐operating internal mechanism regulating reproduction in the catfish is envisaged. The significance of these findings is discussed.