Cryopreservation of spermatozoa in cyprinid fishes

The present study investigated semen cryopreservation in cyprinid fish usin g computer-assisted sperm motility analysis for viability control. Spermato zoa of the bleak, Chalcalburnus chalcoides, were used as a basic model to d escribe the toxic and cryoprotective effects of internal and external cryop rotectants, their most effective concentrations and combinations, the freez ing and thawing conditions, and the effects of equilibration. We also used these data to develop a cryopreservation protocol for Barbus barbus, Chondr ostoma nasus, Ctenopharyngodon idella Cyprinus carpio, Hypophtalmichthys mo litrix, Leuciscus cephalus, Rutilus meidingerii, and Vimba vimba. For all i nvestigated species the optimal extender composition was a buffered physiol ogical sperm motility-inhibiting saline solution containing 10% DMSO and 0. 5% glycin. The optimal sperm equilibration period in the extender was less than or equal to 5 min. Freezing was performed in an insulated box in liqui d nitrogen vapor and it was optimal at 4 to 5 cm above the surface of the l iquid, depending on the species. Thawing was optimal in a 25 degreesC water bath whereby the thawing time ranged depending on species from 15 to 45 se c. This cryopreservation protocol resulted in frozen-thawed semen with 35 t o 65% motile and 5 to 25% locally motile spermatozoa depending on the quali ty of fresh semen. (C) 2000 by Elsevier Science Inc.