ABSTRACT
Aquaculture is an evolving technology for maximizing the survival and growth of captive fish, based upon stringent control of rearing conditions such as photoperiod, water temperatures, salinities, and feeding schedules. However, because the seasonal reproductive cycles of fish are dependent upon combinations of key environmental cues, e.g., fluctuations in food availability, light, and temperatures (Bye, 1990), failure of gonadal recrudescence, ovulation or spontaneous spawning may occur in cultured fish, thus decreasing the fecundity and gamete quality of domesticated broodstock ( Crim, 1991). In early attempts to overcome these difficulties, captive fish have been induced to spawn with various preparations of mammalian or fish pituitary hormones-a technique commonly practiced in many Asian countries today. Still, purified pituitary gonadotropic hormones (GtH) are expensive and crude pituitary h01mone preparations may not be reliable due to problems with storage, potency estimation or, perhaps, adverse immunological reactions to such treatments (Zohar, 1989).
