Changes in Depth of Anesthesia of the Carp Anesthetized with a Constant Level of CO2*1

Abstract

Changes of respiration, behavior, and depth of anesthesia were examined in carp that were individually kept in a chamber supplied with water bubbled with an equi-mixture of CO2 and O2. CO2 had an anesthetic effect on all the carp at Pco2 ≒ 125, 150, and 175 mmHg, but these partial pressures in the ambient water were fatal in 10, 20, and 70 % of the carp, respectively. Although all the carp survived in the experiment using Pco2≒100 mmHg, only 50% of them became anesthetized. The depth of anesthesia progressed with time and the Pco2. Recovery time from anesthetic state was 13–130 min, the mean recovery time being about 40 min in all experiments. The optimum anesthetic concentration for adult carp seemed to be between Pco2 = 100 mmHg and 125 mmHg. © 1988, The Japanese Society of Fisheries Science. All rights reserved.