The control of reproduction in finfish species through GnRH treatments

Fish in captivity can show some dysfunctions, at different levels, in the physiological processes of reproduction, due to the lack of synthesis or release of gonadotropins (GtHs) by hypophysis. As a consequence, a worsening of quality and quantity of spawned gametes, or a lack of egg and sperm spawning, can be observed. The farmers can act on fish reproductive cycle manipulating the environmental parameters of rearing, the diet, the genetics or using GnRH treatments. Nowadays, they are used mainly GnRH, synthesized in laboratory as analogues. These releasing factors, naturally produced by hypothalamus, let to overcome the technological and biological limits of the “traditional” hormonal treatments with hCG, being more effective, cheaper and easily available on market. This article makes a historical survey of the conditioning treatments for fish reproduction and also considers the future perspectives of these treatments, examining the topics that research will have to focus, in order to make these treatments common worldwide, in any hatchery and for each farmed species of finfish.