Reproductive parameters of common carp (Cyprinus carpio L) spawners during natural season and out-of-season spawning.

Common carp spawning characteristics were compared between season and out-of-season periods. There were no differences in the percentage of ovulation, spermatozoa motility and embryo survival to the eyed-egg-stage between the spawning periods. Fish spawned during the season produced oocytes of higher total weight than those spawned out-of-season. On the day exogenous feeding began, larvae obtained in out-of-season spawning were shorter than those obtained during the spawning season. However, the out-of-season larvae started feeding two days earlier than in-season larvae. As a result, seven days after fertilization, larvae obtained during out-of-season had the same length as larvae obtained during season. It appears to be possible to obtain common carp larvae half a year before the natural spawning period without decreasing the quality of gametes and larvae.