Effect of Hypoxia and Energy Conservation Strategies in the Air-Breathing Indian Catfish, Clarias batrachus

Fish in a tropical country like India are frequently exposed to different duration of hypoxia. The effect of hypoxia on the physiology of fish, air-breathing catfish Clarias batrachus were exposed to different duration of hypoxia and its effect on activities of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) were studied in four tissues (heart, liver, brain and muscle). The specific activity of LDH increases in all tissues, which reflects towards onset of anaerobic respiration and decrease in energy demand in all these tissues. In contrast, MDH specific activities were decreased significantly in heart, suggesting involvement of strong aerobic respiration in heart during hypoxia. The present investigation revealed that during hypoxia enzyme activities responded in a tissue-specific manner in the fish C. batrachus reflecting the balance of energetic demands, metabolic role and oxygen supply of particular tissues.