Responses of family and individual selection on growth of snakeskin gourami (Trichopodus pectoralis) across two generations

Abstract

Selecting an appropriate selection method is a fundamental strategy for genetic improvement, enabling breeders to enhance desirable traits, optimize productivity, and ensure the long-term sustainability of breeding programs. This study evaluated selection responses for body weight (BW) in snakeskin gourami (Trichopodus pectoralis) following family and individual selection based on estimated breeding values (EBVs). The base population was formed by crossing three farmed stocks, introducing heterozygosity and structural variation that influenced early generation outcomes. Although methods were applied in different generations, family selection was applied to the G₀ generation, resulting in a negative realized response (−0.155 g), while individual selection was applied to the G₁ generation, resulting in a positive realized response (0.929 g). Low heritability estimates (0.025–0.175) and moderate to high common environmental effects (0.059–0.219) were observed. Although direct comparisons between selection methods must be made cautiously due to the population restructuring, individual selection demonstrated the potential for meaningful genetic gain. The cumulative selection response over two generations was 0.774 g, corresponding to an improvement of 35.67 % per generation. These findings highlight the importance of considering population structure in breeding evaluations and support the value of individual selection strategies to improve growth traits in aquaculture species under complex population conditions.