Genetic improvement of farmed tilapias: the growth performance of eight strains of Oreochromis niloticus tested in different farm environments

Abstract

Results from two consecutive generations of testing to evaluate the growth performance of eight different strains of Nile tilapia ( Oreochromis niloticus) in eleven different farm environments are reported. The eight strains include four new strains recently imported to the Philippines from Egypt, Ghana, Kenya and Senegal; and four established Asian farmed strains popularly known in the Philippines as ‘Israel’, ‘Singapore’, ‘Taiwan’ and ‘Thailand’ strains. The test environments were chosen to cover a wide range of Philippine tilapia farming systems, from simple ponds, as used by backyard farmers, to more intensive systems: fertilized ponds, ponds fertilized with on-farm agricultural residues, rice-fish systems, cages, and three tilapia hatcheries (satellite stations) located in different regions of the island of Luzon. During the first generation trials in 1989, individually tagged fingerlings bred from the founder populations (total 7652) were communally reared in all test environments for about 90 days. In 1990, the second generation trials were made as a part of a complete diallele crossing experiment (8×8 strains). Data on 3420 individually tagged fingerlings of pure strains communally reared in eight test environments were used for the study. The results indicated highly significant differences among the growth performances of the eight strains. Moreover, with the exception of the Ghana strain, the newly introduced African wild strains performed as well as or better than the most widely farmed Asian strains. The importance of strain×test environment interaction over the investigated range of test environments was low. The implications of these results for developing a breeding program for tilapias in the Philippines are discussed.