Effects of stocking density on survival and growth indices of common carp (Cyprinus carpio).

The effects of social interactions on survival, growth indices and competitive behavior of common carp (Cyprinus carpio) at four stocking densities (350, 400, 450 and 500 fish per hectare) were investigated. A poly-culture of Chinese carps was implemented for 7 months in 12 culture ponds each 10 hectares in size at Dikjeh area, Golestan province of Iran. Monthly biometrical characteristics such as total length, weight, and condition factor and growth rate were measured. The introduced common carp weighing on average 45g reached 705g after 7 months. With increase in common carp density up to 450 fish per hectare, growth indices including secondary weight, growth rate, SGR and fish biomass showed no significant differences (P>0.05), whereas 500 common carp individuals per hectare caused secondary weight, growth rate and SGR indices decrease significantly (P<0.05). At this density, fish biomass showed significant increase (P<0.05). Based on the results of this study, we conclude that common carp can be successfully cultured up to a density of 450 fish per hectare.