Performance and survival of three red tilapia strains (Oreochromis spp) in pond environment in Kedah state, Malaysia

Abstract

Growth performance (body weight, standard length, body width and depth) and survival of three red tilapia (<i>Oreochromis</i> spp) strains from Malaysia, Taiwan and Thailand were evaluated using 2,867 records collected on individually tagged fish after a period of three-months of communal rearing in an earthen pond. The statistical model used to analyze the data included strain, sex and their two-way interaction as fixed effects and age from stocking to harvest and initial weight as linear covariates. The effect of strain was highly significant for all body traits (P< 0.001). The Malaysian strain had the fastest growth rate, whereas the lowest performing strain was that from Thailand. The growth performance of the Taiwanese strain was intermediate. Across strains, body measurements of red tilapia females were significantly (P< 0.001) smaller than those of males. The strain by sex interaction was statistically significant (P< 0.05 to 0.001). We also analyzed survival rate of the fish from stocking to harvest, using a generalized non-linear model. Survival was considered as binary trait, and the model assumed that the data followed a binomial distribution, with a logit link function. In contrast to the results for body traits, survival rate was poorest for the Malaysian strain (66.4%). The difference in survival rate between Taiwan and Thai strains (78:5 vs. 80.6%) was not statistically significant (P> 0.05). Our results suggest that there are genetic differences in growth performance and survival among red tilapia strains from Malaysia, Taiwan, and Thailand. They are thus being included in a complete diallel cross to further examine the additive and non-additive genetic performance of the strains before forming the base population for future genetic selection. In this paper, we present an outline and key activities of the planned genetic improvement program for red tilapia in Malaysia.