Evaluation of the repeated use of xylocaine as anesthetic for the handling of breeding carp ( Cyprinus carpio)

The present work presents the results of repeated anesthesia on carp ( Cyprinus carpio) ( n = 151) with xylocaine, 12 or 24 h after a prior application. Each fish was dipped in 20 liters of water containing 3.5 g of xylocaine until opercular movement ceased. The fish were weighed and measured and Ricker's multiple condition factor ( K m ) was computed. The fish were randomly assigned to one of two subgroups: one which was anesthetizied 12 h after the first anesthesia, another which was anesthetized 24 h after. The following variables were considered: the induction time or time to anesthesia, the K m , the time out of water and the recovery time. From these we conclude that xylocaine is suitable for repeated anesthesia at 12 and 24 h, as no differences could be detected for the variables of interest for any of the treatments. The ease of its application and the values obtained for the variables advanta-geously compare with those of other anesthetics.