EFFECTS OF DIFFERENT SIZED PRUSSIAN CARP (CARASSIUS AURATUS GIBLIO BLOCK) POPULATIONS ON THE PRODUCTION OF COMMON CARP (CYPRINUS CARPIO L.) YEARLINGS

摘要

The success of the Hungarian pond fish culture is depending on the common carp (Cyprinus carpio) production. In Hungary the production time of the market size carp is three years. The main problem with this method is the long payback time. Therefore the breeders have to pay attention for the safety of the production. Always the rearing of the one year old carp is in focus, because it basically determines the yields of the two consecutive years. At present one major issue is the production without thepresence of Prussian carp (a crucian carp, Carassius auratus gibelio), that is affecting the nursing and fingerling rearing of the common carp, because in carp fingerling culture a spread of the Prussian carp caused significant problems. The negative effect of Prussian carp is a complex issue: while in the ponds, it occupies habitat from common carp, it competes for natural- and formulated feedstuffs. Due to the fact that the Prussian carp has a worse feed conversion ratio and significantly lower market price than common carp, the income per hectare is lower in ponds where the Prussian carp is present.