Studies on the effect of biocides on changes in physiological profiles in a teleostean fish, Mystus cavasius (HAM.)

The present paper deals with the effects of certain biocides on the haematology and respiratory metabolism in an air breathing fish, Mystus cavasius (Ham.). DDT. Metacid and Unizeb cause anaemia (i.e. decrease in RBC counts and Hb content) whereas the treatment of Endrin, Urea and Phenol brings about polycythemia (i.e. an increase in RBC counts and Hb content) in this fish. Endrin elevates the oxygen consumption of this fish by nearly 40% while the treatment of DDT, Unizeb and Metacid causes significant decrease in oxygen consumption. The effect of different biocides on the physiological changes were more pronounced in fishes of smaller size as compared to large speciemens. The value of TLm (median tolerance limit) of different biocides have also been measured. In polluted water the frequency of surfacing (i.e. they depend more on aerial respiration) increased in contrast to gill respiration. The reason for and mechanism of such changes are discussed in this paper.