The present study was undertaken to know the effect of common mixed pulp and paper mill
effluent discharge released from century pulp and paper mill Lalkuan, Nainital Uttarakhand
on the blood morphology of Heteropneustes fossilis (Singhi). The various morphological
changes were observed in the specimen, randomly collected with the help of cast net from
(3 sites) different locations. The maximum changes were observed in the specimen
collected from site 3 in compare to site 1 and 2 respectively. The formation of inclusion
bodies, sickle cells, Cabot rings and ovalocytes were recorded along with nuclear fusion,
membrane disruption and cell clumping of blood cells in the specimen collected from the
site 3 (i.e. nearer to source of discharge) while in the specimen collected from site 2, the
formation of tear drop cell, target cells, spherocytes and bi-nucleated cells were recorded
along with the activity of cell clumping. The changes were found less in the specimen
collected from site 1 in compare to the specimen of site 2 and 3 i.e. formation of ovalocytes,
spherocytes and microcytes with the activity of membrane degeneration and agglutination
in blood cells.