Replacement of supplementary feeding with enhancement of natural productivity by pond fertilization for growout of the Gulf killifish (Fundulus grandis) was evaluated in 2 successive trials stocked at 330,000 fish/ha and 150,000 fish/ha, respectively. The first trial compared fertilization only, fertilization plus feeding at 3% body weight, and feeding at 3% body weight only in replicated 0.1 ha ponds. Growth rates were not significantly different, although days to marketable fish were 80-94 in the fertilized treatments and 100-107 in the fed-only ponds. Overall production averaged 710 kg/ha; 689 kg/ha in fertilized-only ponds. The second trial compared fertilization only, feeding at 5% body weight, and feeding at 5% body weight split into 2 daily feedings. Again growth rates did not significantly differ. Low fall temperatures prevented attainment of marketable fish. Both labor and material costs are substantially reduced by using fertilization only.