No abstract

Different cell types found in the peripheral blood of Cknna punctatus, an air-breathing freshwater fish have been characterized and identified using morphological, morphometric, cytochemical and autoradiographic techniques. Some of the cytochemical methods used, particularly that of differential staining of haemoglobin have been developed and used for the first time in fishes.

The results of a series of experiments on Channa punctatus previously conditioned to a complete synthetic diet and later fed vitamin C deficient diet for 210 days followed by 30 days of recovery with fortified vitamin C ration are reported. The survival, growth, morphological abnormalities and biochemical changes in tissue ascorbic acid and cholesterol levels were studied.Deficiency of vitamin C resulted in a mortality of up to 25% and retarded growth accompanied by anorexia and loss of weight. Marked skeletal abnormalities, viz., lordosis, scoliosis and degenerative changes in the thoracic vertebrae were revealed by X-ray studies. Biochemical investigations showed a significant decrease in blood and kidney ascorbic acid levels within a month of feeding the deficient diet. A prolonged deficiency beyond 150 days resulted in a rapid rise in the cholesterol content of the liver. These biochemical changes were reversed when vitamin C was added to the ration.

Response of Channa puricrarus to acidic water was studied by exposing fishes to pH 3.5.4.5, 5.5 and 6.5 for 6 weeks. Growth and mortality data indicated increasing stress as the acid level in the ambient water increased. While no mortality was recorded at pH 6.5, a distinct loss of weight compared to continuous gain in body weight in control fish indicated stress. As the pH level decreased, the rate of loss in body weight increased accompanied by mortality which rose to as high as 60% within 3 weeks in fishes exposed to water at pH 3.5.Haematological investigations confirmed the general stress indicated by growth and mortality data. Thus. RBC and related values indicated overall polycythemia. However, eosinophils, basophils. and large and small lymphocytes showed a distinct fall in number as compared to the control .Correlated haematopoietic studies revealed that both the initial and penultimate stages in RBC and neutrophil development recorded an increase parallel to that observed in peripheral blood, but intermediate stages. probably because they were unable to keep pace with the fast turnover, showed a relative decrease.Biochemical investigations showed an increase not only in blood glucose level but also in liver glycogen content. However, there was a significant decrease in muscle glycogen reserves.The significance of these changes is discussed.

SUMMARY Sound producing apparatus in Sisor rhabdophorus is described. The apparatus is formed by the modification of the neural spines of a few of the anterior vertebrae and the first interspinous bone of the dorsal fin. Significance of sound production in this species is discussed.