Genetic improvement of farmed Nile tilapia (Oreochromis niloticus) through selective breeding in Egypt

Nile tilapia, Oreochromis niloticus is one of the most economically important African fish. The present study illustrates the current state of a selection program that mainly focuses on growth rate of farmed Nile Tilapia. Nile tilapia populations were collected from three geographically separated locations; Kafr El-Sheikh (K), Faiyum (F) and Serow (S). The selection based on fish age, condition factor and the genetic variation between populations; parents of two years, high Condition Factor (CF) and genetically distant parents were selected. Fish were fed on different nutrition regimes in different seasons. Simple Sequence repeats (SSR) technique was applied to assess the genetic variation between the studied populations. The molecular examination revealed that Kafr El-Sheikh (K) and Faiyum (F) populations are the most genetically distant populations with the lowest genetic similarity, 0.103. Therefore, two combinations of mating were done between (K) and (F), (F♀X K♂) and (F♂X K♀). Moreover, selected males and females from each population were also mated; (K♀ x K♂), (F♀ x F♂), (S♀ x S♂). Differences in growth rate among the produced strains were recorded during a period of five months revealing that (F♂ × k ♀) followed by (F♀× k ♂) & (F♀× F♂) strains have the highest significant values of total weight. Therefore, these strains will be considered as brood stocks for the coming selection. The work in this investigation will continue for at least another four years.