The rate of thermal exchange in a teleost, Tilapia mossambica.

Abstract

Excess tissue temperatures of a fish in a stable thermal environment were estimated. In fish weighing 40 to 200 g, mean excess muscle temperature was 0.44 °C and brain, 0.45 °C. A significant high local excess temperature (0.80 °C) was observed in the isthmus, immediately under the skin just anterior to the pelvic girdle. Mean excess muscle temperature in fish weighing less than 40 g was 0.15 °C.The rate of thermal exchange of fish was estimated by measuring the tissue temperature after the fish was placed m a bath 5 °C cooler than ambient. The slope of a double logarithmic plot of the coefficient of cooling versus body weight was −0.3. The coefficient was 1.8 °C/min per °C difference for fish weighing 1.0 g and was 0.4 for fish weighing 100 g.