The growth performance of three commercially available strains of Nile tilapia (Oreochromis niloticus) fed one of four different commercially available feeds during nursery and grow-out was assessed in Kenya. Each of the 12 treatments (three strains x four feeds) had four replicates (two in each of two ponds) at each of the two locations (Western and Central Kenya). The experiment tested starter feeds (phase 1, lasting 85 days) and grower feeds (phase 2, lasting 127 days). There were statistically significant differences in growth and feed conversion ratio (FCR) for fish grown on different starter and grower feeds within both areas, but not between fish strains at harvest in Central Kenya where growth of all strains was poor on all feeds. The mean weight over all strains at the end of the starter phase in Central Kenya was 5.9 g (FCR 2.4) and at final harvest 53.6 g (FCR 3.6). In Western Kenya, where temperatures are 5.4  °C greater on average than Central Kenya, mean weight over all strains at the end of the starter phase was 19.5 g (FCR 2.2) and 189.8 g (FCR 1.9) at final harvest. The most cost-effective combination was formulated feed with approximately 35 % protein and a strain with a better FCR than the others tested resulting in 38 % less average feed cost than the next best combination. Mash, the cheapest feed tested, provided such poor weight gain that feed costs per unit gain were higher than for other feed/strain combinations. Production costs in Central Kenya were twice that in Western Kenya and suggest niche business models will be required for that region with careful choice of farm sites. Performances of key inputs (feeds and strains) available in Kenya for tilapia aquaculture vary significantly, and some combinations with sound management provide better outcomes that could determine whether farming is profitable or not.