Hepatic Glutamate dehydrogenase activity and the presence of ammonia and urea in the circulatory fluid of Channa gachua in water-restricted condition

Ammonia is the chief excretory product in fishes. However, non-availability of enough of water in the habitat, may lead to the formation of urea, in fishes. In the present study, the possible role of urea formation to avoid the toxicity of ammonia under water-restricted condition was tested in Channa gachua. Circulatory urea and ammonia were estimated in the blood of the fishes and glutamate dehydrogenase activity was measured in the hepatic tissue. From the present study, it is found that blood ammonia in Channa gachua showed a decreasing trend from 1 to 10 day and blood urea showed a steady increase during the experimental period. The correlation study between the blood ammonia and blood urea concentrations in C. gachua establishes the presence of definite relationship between these two parameters. However, hepatic glutamate dehydrogenase activity showed a fluctuating trend. Presence of high circulatory urea in the experimental fish indicates that ureogenesis may get activated, if the fishes face water-limitation.