Possibilities of commercial exploitation of rheophilic fish in captivity: A review

Resumen

The majority of fish species reared in captivity presents some form of reproductive dysfunction. In females may appear failures of final maturation of the ova, ovulation and the spawning; while in males occurs a decrease in the production of milt and in its quality. These dysfunctions appear due to the modification of the natural conditions of reproduction of the fish in captivity, originated from the lack of external stimuli needed for induction the pituitary to release of gonadotropins. In overcoming these disturbances have been used the hormones of reproduction for over fifty years, initially as pituitary extracts to stimulate the reproductive processes of spermiation, ovulation induction and spawning. More recently the hormones derived from fish and mammals, such as the carp, salmon and chorionic gonadotropin, and employment of new methods, with the factors releasers of gonadotropins (GnRH), which induce the release of gonadotropin own pituitary decreasing the markest failures in creations in captivity. The development of synthetic agonists of GnRH (GnRHa), highly powerful, consist of the new generations of therapies to hormonal manipulation, creating new possibilities with the use of hormones for the control of reproductive processes in aquaculture. The products developed more recently incorporate the GnRHa in polymeric system release long, with the effects of the hormone extending by extensive periods that last for days and even weeks. These systems eliminate the need for multiple treatments, in addition to induce the development of germ cells and the synchronization of multiple spawns. These different forms of GnRH recently found and their better knowledge certainly will be widely used in therapy for spawning. New strategies must be developed to enable a improve achievement of spawning, possibly with research to correct levels of GnRH rolling stock.