DIETARY FAT AND TEMPERATURE TOLERANCE OF GOLDFISH

Abstract

Resistance of goldfish to low as well as to high temperatures may be changed by feeding diets containing different fats in high concentration. There is no evident relationship between melting point of the natural fats (pilchard oil, herring oil, and lard) and tolerance to cold. Hydrogenation of pilchard oil used in the diets reduces resistance of goldfish to both low and high temperatures. Fish fed on hydrogenated cottonseed oil show a similar reaction to high temperatures. These findings are contrary to the theory that increased thermal resistance is associated with higher melting point fats. It is suggested that the presence of double bonds in the lipids is important in maintaining the integrity of the plasma membrane.