Hormonal Control of Reproduction in Fish for Induced Spawning

Reproduction in fishes is regulated by external environmental factors that trigger internal mechanisms into action. The final event of the reproductive cycle, the release of eggs and sperm resulting in spawning, can be controlled by either placing the fish in an appropriate environment or by changing the fish’s internal regulating factors with injected hormones or other substances. The internal mechanisms that regulate spawning are similar for most fishes. The external environmental factors that control reproduction, however, vary considerably among species. For this reason, more is known about the internal regulatory mechanism of fish reproduction than the specific environmental requirements for spawning each species.