Assessing Genetic Improvement Potential in Nile Tilapia Lines Under Controlled Breeding Programme in Ogun State

This study assessed the genetic improvement potential of Nile tilapia (Oreochromis niloticus) through selective breeding using phenotypic selection criteria within a controlled breeding programme established at an aquaculture research station in Ogun State, South West Nigeria. Genetic improvement through selective breeding offers one of the most cost-effective pathways to increasing aquaculture productivity, yet structured breeding programmes for tilapia remain rare in Nigeria. Three tilapia lines representing different hatchery origin populations were crossed in a 3x3 full diallel mating design to estimate combining abilities and heritability for growth traits. Offspring from 27 family groups were reared under standardised conditions over 20 weeks. Growth traits including weight at 10 weeks, weight at 20 weeks, specific growth rate, and fillet yield were measured. Genetic parameters were estimated using restricted maximum likelihood analysis. Results showed heritability estimates for body weight at 20 weeks ranging from 0.28 to 0.41 across lines, indicating moderate genetic variation amenable to selective breeding. General combining ability effects were significant for all traits, confirming substantial additive genetic variance. Specific combining ability effects were significant for fillet yield, suggesting the potential for crossbreeding to capitalise on non-additive genetic effects. The line originating from a certified improved GIFT strain background showed the highest estimated breeding values for growth. The study provides quantitative genetics data to underpin a formal tilapia genetic improvement programme in Nigeria and recommends the establishment of a national tilapia breeding nucleus farm to accelerate genetic gain delivery to commercial producers. Keywords: selective breeding, Nile tilapia, heritability, genetic improvement, aquaculture