Muscle metabolism in Antarctic fish

1. The energy metabolism of Antarctic fish muscles is discussed in relation to environmental temperature and the fishes' locomotory habits. 2. The predominant body form in terms of body shape and muscle fibre type is typical of fish which employ burst subcarangiform swimming and sustained labriform swimming. 3. Enzyme and metabolite data are indicative of a high potential for creatine-phosphate hydrolysis, even when compared to warm animals. 4. The limited data concerning oxidative metabolism may indicate that enzymatic potential is normal compared to warmer animals of similar body form, but an increase in mitochondria may be required to maintain rates of oxygen utilization equivalent to those of warmer species. 5. It is argued that low temperature was not the primary selective pressure in determining the energy production patterns, and that locomotory methods employed by the fishes were a major determining factor.