ABSTRACT
A fish farm should have a minimum of two brood fish stock ponds (in addition to the pond for replenishment), so that the males and females can be kept apart before spawning. The introduction of fish for spawning is preferably done toward evening. The carefully selected and conditioned breeders should spawn the next morning. The selection of spawners for a redd is important. In some redds spawning takes place when it should and in others is considerably delayed. In spawning (hatching) ponds rich in vegetation the oxygen content in the morning hours often decreases to a lethal point, which may cause total mortality among young fry. The hibernation of fingerlings in rearing and foraging ponds is permitted only under exceptional conditions, since round-the-year filling with water deteriorates the sanitary conditions and hydrochemical regimes of these ponds, reduces natural fish productivity, and eliminates the possibility of determining the output from rearing ponds over the vegetative growth period and hibernation period.
