Two strains of Nile tilapia, Oreochromis niloticus, were developed through mass and pedigreed selection techniques. Performance of the mass-selected line has been tested against a control and commercial lines used by the farmers. On station testing indicated an improvement of 35% over the control, the base population, from which the selected O. niloticus stock was developed. In an initial farm trial, the improved O. niloticus stock performed 51% better than the commercial line that is regularly distributed by a commercial hatchery to the local farmers. Additional farm testing of the mass-selected line is still in progress. The mass-selected line is currently being evaluated against the pedigree selected line. The best candidates will be identified and used in the pedigree selection program.