Water and Electrolyte Balance of Goldfish Under Conditions of Anoxia, Cold and Inanition

Abstract

Small goldfish ( Carassius auratus), average length 38 mm, were exposed to three conditions of stress, namely, acute anoxia, cold and inanition. Acute anoxia did not alter Na or K content of the body, but water increased 0.85%. Exposure to 4.0°C for 48 hours increased the water content 2.15%, but no change occurred in the absolute values of Na and K. Inanition for 2 and 7 weeks caused a progressive loss in dry weight without significantly altering the absolute amount of water. However, when total water was calculated on a dry weight basis, the increase was 3.81% for 2 weeks fasting and 6.74% for 7 weeks fasting. Sodium increased in absolute amount with fasting while K decreased. This inverse relationship showed a high correlation. For every milliequivalent of K lost, 1.2 mEq of Na was taken up. An important difference between the period of 2 and 7 weeks of fasting is discussed with respect to Na and K and their role in carbohydrate, fat and protein depletion.