The acute toxicity of heptachlor for freshwater fishes

Abstract

The effect of heptachlor on tissue energy reserve and on serum glucose and lactate levels was studied in 9 nutritionally important species of fish from a tropical environment. The breakdown of glycogen was highest in major carp species followed by snake-headed fish and then by catfish. There was an inverse relationship between the concentration of heptachlor and the fall in liver, muscle and brain glycogen contents. An increase in renal glycogen content at a concentration of 3 ppm heptachlor was attributed to increased glucose levels and to an attempt by kidney tissue to conserve energy. Tissue glycogenolysis was indicated by increased levels of serum glucose and lactate. The fall in tissue glycogen content after exposure to heptachlor is discussed in relation to damage to surface cells and blood capillaries of the gills, to interference in oxygen intake and transference to deposition of a thick layer of mucus over the gills. The differential effect of heptachlor may be due to the biochemical compartmentation of fish tissues and to deposition of the toxicant itself.