A genotype by environmental interaction study was conducted using the live weight data collected from three discrete spawning seasons of Genetically Improved Farmed Tilapia selective breeding program in Malaysia. Two production environments were used to grow-out the progeny, namely, cages and ponds. The analysis was carried by using animal mixed model and treating live weight in cages and in ponds as two different traits to determine the genetic correlation, which was used to quantify the genotype by environmental interaction for these two environments.