A Review on Melatonin and its Prospects in Fish Aquaculture
Current research and data available suggest pineal organ is the mediator that converts the information of photoperiod into melatonin. The source of melatonin is not only pineal gland but gastro-intestinal-tract (GIT) also produces a substantial amount of melatonin. The detection of melatonin-synthesizing enzymes, N-acetyltransferase and hydroxyindole-Omethyltransferase in the GIT confirmed extra-pineal melatonin synthesisthat the pineal and gut melatonins are two different systems set to perform different physiological processes. The degradation of melatonin in liver occurs only when it reaches certain threshold level. Melatonin regulates the physiological process of growth, food intake, stress and immune system and reproduction as a result of specific behavioural rhythms. Not much knowledge has been gathered on the role of melatonin in relation to physiology in fish.
Ngasainao MR and Lukram IM