Primary production in intensive fish ponds and a complete organic carbon balance in the ponds

Abstract

Determinations of primary productivity, water respiration and other biological and chemical parameters were carried out in earthen experimental ponds. The ponds were stocked with common carp ( Cyprinus carpio) or Tilapia hybrids in monoculture. The stocking rates were between 7,000 and 20,000 carp/ha, and 20,000 and 100,000 Tilapia/ha. The fish biomass was up to 23 ton/ha. Gross production reached 11,090 mg C/m 2 per day in the super-intensive pond of 100,000 Tilapia/ha. The primary production was found to be higher in the more intense pond within the same species, and higher in the carp ponds than in the Tilapia ponds. A complete organic carbon balance was calculated for each pond. The calculations summed up all the sources of input and output of organic carbon in the pond and calculated the surplus. The annual organic carbon surplus was found to increase with fish density within the same species and reached 8,900 kg C/ha per year in a pond stocked with 20,000 carp/ha. It was also found that the organic carbon surplus was 3–4 times higher in the carp ponds than in the Tilapia ponds.