Abstract

The number of aquatic species currently under domestication efforts is rising rapidly, due to the development of commercial aquaculture. For domestication and the establishment of a sustainable aquaculture industry, the control reproduction processes of fish in captivity, and to acquire high quality seed, is necessary. The fish reproductive cycle is separated in gametogenesis (of growth) and oocyte maturation and spermiation (of maturation). These are controled by the reproductive hormones of the brain, pituitary and gonad. Environmental and endogenous physiological information reach neuroendocrine system that regulates pituitary and gonadal functions. The most commonly reproduction dysfunctions in cultured fish are the unpredictability of final oocyte maturation (FOM) in females, and the lack and less quality of sperm in males. These problems are due to the fact that the fish in captivity does not have the same conditions in the spawning grounds, and as a result, there is a failure of the proper hormonal regulation. Failure of the pituitary to release gonadotropin (GTH-II), one of the hormones involved in the regulation of reproduction, is the result of unsucssesful ovulation. Actually two type of GTH are identified. They are differing from structural and chemical roles. GTH-I also name as FSH, involve in vitellogenesis or spermatogenesis (initial stage of gametogenesis), and GTH-II name as LH are involve in FOM and spermiogenesis and spermiation. The control role and function of the hormone involve in reproduction are described and reviewed in the present paper.

Key word: GTH-I, GTH-II, GNRH, teleost, gametogenesis.