Abstract: To assess the effects of selective breeding in GIFT tilapia (Oreochromis niloticus), we measured the disease resistance and growth performance of 42 families of GIFT tilapia F₅ generation, taking F₀ generation and hybrid tilapia (Oreochromis aureus×O.niloticus) as control groups. The results show that the survival rates of 36 families of F₅ generation were higher than that of F₀ generation, and the survival rates of 22 families were higher than that of hybrid tilapia after Streptococcus agalactiae infection. The disease-resistant breeding value was – 0.158 – 0.086 among different families. The absolute growth rates of 27 families were higher than that of F₀ generation. The correlation coefficient between the survival rate and the body mass was negative, and the quantitative value was – 0.033. According to the comprehensive comparison among the survival rate, disease-resistant breeding value and absolute growth rate for 42 families of F₅ generation, we have screened seven families (2^#, 3^#, 4^#, 6^#, 28^#, 31^#, 35^#) which were best-performing and can be used as breeding parents of F₆ generation. The results indicate that the disease resistance and growth performance of GIFT tilapia were improved significantly after five generations' selective breeding.