Genetic parameters and genotype by environment interaction for growth of Nile tilapia in low and optimal temperature

Tilapia is an economically important species cultivated mostly in tropical countries. The adaptability and tolerance of this species to diverse environments and systems has resulted in a rapid expansion of tilapia farming. Water temperature is recognized as one of the most important factors influencing growth of tilapia. The optimal temperature for growth of most tilapias range from 26°C to 30°C, while the lethal temperature is 10°C. Activity and feed utilization will decrease when temperature falls below 20°C (Chervinski, 1982). Therefore introduction of Nile tilapia (O. niloticus) to subtropical and temperate regions, will lead to poor growth and massive mortality during over-wintering. Performance and robustness of tilapia in temperate climates may be improved by increasing growth rate and pond survival at low temperatures. This will contribute to increased production of tilapia by either extending the growth season or by increasing the number of crops per year in these environments.