Polyhouse driven raised-temperature induces cichlid tilapia to breed during winter

Abstract

Two experiments were performed to examine the impact of global warming on the growth of some carps, and growth and breeding performance of tilapia in small holding tanks using polyhouse model for testing the green house driven raised-temperature on breeding performance of tilapia during winter months. Advanced fry of fish (rohu, bata, paku and common carp) as well as semi-adult male (2) and female (2) tilapia were reared for 91 or 98 days. The net weight gain of tilapia did not differ between outside and inside the polyhouse. Growth differences in rest of the fishes tested were not significant between enclosed and outside polyhouse. Tilapia held in enclosed polyhouse tanks bred and produced fry with numbers ranging from 28-36 / tank, whereas, there was no trace of breeding in tanks placed outside the polyhouse with ambient temperature. Water temperature remained to be significantly higher in the enclosed polyhouse compared to outside tanks. Raised water temperature of around 2.93°C inside the polyhouse over the ambient temperature outside was responsible for breeding activities of multiple spawner cichlid tilapia Oreochromis mossambicus. However, water quality parameters did not differ between the enclosed and outside polyhouse. It may be concluded that the benefit of closed polyhouse may be profitably used by the fish farmer for inducing breeding in tilapia and growth enhancement in other Indian fishes during winter months and colder region of the country in general.