Reproductive Endocrinology of the Tropical Walking Catfish, Clarias batrachus.

Basic information on reproductive endocrinology is lacking in tropical fishes, although tropical areas harbour a wide variety of fish species. This paper provides information on plasma sex steroid levels in tropical walking catfish maintained under stable warm water conditions for two years. It was ascertained that males and females maintained mature gonads capable of undergoing ovulation at any time during the experimental period. Fish never underwent spontaneous spawning, but a single HCG injection could induce ovulation at any time of the year. Such fish also ovulated and spawned in response to water level and temperature manipulation. Changes in water temperature probably increase the sensitivity of fish to the change in water level. Endocrine changes following HCG injection were also monitored.