The Oxygen Capacity of Goldfish (Carassius Auratus L.) Blood in Relation to Thermal Environment*

Abstract

The Roughton & Root (1945) modification of the Van Slyke method for measuring haemoglobin content of blood as carboxyhaemoglobin is satisfactory for fish blood, provided at least 0·1 ml. is available. Measurements of iron content are of doubtful value in estimating the oxygen capacity of fish blood. The following photometric methods of determining haemoglobin content were found to be unreliable with fish blood : acid haematin, alkaline haematin and cyanhaematin. The following photometric procedures gave satisfactory measurements of the haemoglobin content of fish blood: Haldane (carboxyhaemoglobin), oxyhaemoglobin and pyridine haemochromogen. Blood from goldfish acclimatized to temperatures near the extremes of their thermal range shows no difference from normal blood in oxygen capacity.