Breeding lines in tilapia breeding refer to distinct and selectively bred populations of fish that have been developed to exhibit specific traits or characteristics. Each breeding line is established with a specific breeding objective in mind, and over successive generations, the selected traits are emphasized and refined. This selective breeding process facilitates rapid genetic gain for the targeted traits and the creation of specialized lines tailored to different market preferences or production objectives. Besides these, by focusing on one trait or a set of traits within a particular line, we can minimize the impact of negative genetic correlations with other traits that might hinder overall improvement . Implementation of line breeding, together with genomic selection in GenoMar breeding nucleus has tripled our rate of genetic gain, compared to the pedigree-based selection (Figure 1). Further, simulation shows that engaging in precision breeding for 300g through a distinct line breeding program yields an additional 138% genetic gain for weight at 300g over the next ten years when compared to selecting using balanced breeding approaches (Figure 2).