Anaerobic metabolism in goldfish (<i>Carassius auratus</i>)

Abstract

At 20 °C goldfish survive anaerobic conditions for only a few hours while at 4 °C survival is extended to several days. During the course of low-temperature anaerobiosis there was a rise in blood glucose and lactate, a decline in liver glycogen concentration, and an increase in liver water content, while liver size remained constant.The better cold anaerobic survival of winter and hypophysectomized goldfish compared with spring and sham-operated animals was correlated with greater glycogen stores in the livers of the former. It is concluded that liver glycogen is a necessary energy source during cold anaerobiosis, and it is suggested that the resulting hyperglycemia may represent a mechanism to increase glycolytic energy yield. Cold anaerobiosis also resulted in elevated liver glucose-6-phosphatase (EC 3.1.3.9) activity, suggesting an increase in glycogenolysis, but no change in glycogen phosphorylase (EC 2.4.1.1) activity. While cold anaerobic survival is short term it is possible that liver glycogen may sustain goldfish for longer periods at low oxygen levels through a mixed aerobic–anaerobic metabolism.