Farm fish production is affected from seasonal changes as all of the agricultural activities does. Fish are known as coldblooded animals and their vital activities are directly associated with water heat. A growth failure is observed for the fish whose metabolism activities are low in their spawning periods. At this juncture; a natural extension in breeding time is going to be discussed because of the inability of intervening the fish or water heat. Another effect of seasonal changes is about egg take. Fish, lay egg in the seasons which are at specific water temperatures and daylight time. Except these seasons, obtaining egg is going to be possible by changing water temperatures and illumination time in terrestrial production facilities in which broodstock fish exist. This can be defined as ‘ the photoperiod application ‘.
