Compound feeds and cereals as potential tools for improved carp Cyprinus carpio production

Appropriate supplementary feeding is of increasing importance in common carp Cyprinus carpio pond aquaculture, not only with respect to production issues but also as a sustainable tool for maintaining environmental quality. We studied the effect of different supplementary feeding regimes (no supplemental feed, cereal grains, pelleted feed, pelleted feed with lowered phosphorus content, and extruded feed) on growth performance, water quality, natural food availability, phosphorus budget, fish body composition and economic performance in 10 experimental ponds stocked with 3 yr old carp at a density of 363 fish ha⁻¹ over a 4 mo period. The type of supplementary feed had no significant influence on water variables, with the exception of low-phosphorus pelleted feed which increased conductivity (p < 0.05). No significant differences were observed in zooplankton density. Harvested fish had significantly (p < 0.05) higher dry matter content and considerably higher phosphorus content under all treatments compared with fish at the beginning of the experiment. The use of cereals and extruded feed improved carp growth, while the physical qualities of the feed (higher resistance to nutrient leaching) resulted in lower nutrient concentrations in effluent water. Profitability was increased with application of cereal grains and decreased with all pelleted and extruded feeds. Hence, the use of cereal grain feed generated higher economic and environmental benefits than selected pelleted and extruded feed.