A novel management plan allowed tilapia Oreochromis niloticus to graze on a microbial mat ecosystem dominated by the cyanobacterium, Oscillatoria. Shallow feeding lanes were opened in a sequential arrangement to permit tilapia grazing while the microbial mat matured in adjacent lanes. Tilapia grew rapidly on microbial mat until their biomass reached 1 g tilapia/50 cm2 of mat. At greater densities, the mat was depleted faster than it was replaced. In Dominican Republic field ponds, there were no significant differences in weight or length increases between the three treatments (microbial mat feed, microbial mat + commercial feed, commercial feed) during the 42-day feeding trial. Therefore, from a growth perspective, microbial mats are competitive with commercial feeds which may be entirely spared by microbial mat feed From an economic perspective, low labor costs in the Dominican Republic could make microbial mats an economically superior form offish feed for tilapia.