Experiments using commercial fertilizer in distilled water indicated that an N–P–K–CaCO3ratio of 4:1:1:8 gave most economical plankton production. Pond waters in Central Alabama were found to require the addition of nitrogen, phosphorus, potash, and lime for maximum fish and plankton production. For use in pond waters, the above ratio was used with the amount of phosphorus doubled, giving a 4:2:1:8 ratio of N–P–K–CaCO3. The application of this mixture of commercial fertilizers gave a fish production of 578 pounds per acre, compared to 134 pounds per acre in the unfertilized control.