ABSTRACT
In any form of rearing, the basic problem is to obtain the stock to initiate the culture cycle. In vertebrates juveniles are produced through sexual reproduction. In this category fish, particularly marine species, are characterized by their high fecundity; it is not unusual for a female to spawn several thousand eggs per kilogram body weight. The control of sexual reproduction is therefore the starting point of aquaculture activities. The ova and spermatozoa of adult fish differentiate from the primordial germ cells. In most fish the sexes are separate; although hermaphrodites are found. The maturation of male fish usually proceeds without interruption in captivity and there are generally few difficulties in obtaining sperm emission from fish kept in tanks. Fish, being poikilotherms, are more active at warm temperatures. Bass consume food more actively between May and November than at other times of the year. This leads to the accumulation of fatty reserves in the mesentery around digestive tube of non-oily fish.
