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ABSTRACT

Pollution of water with chemicals, heavy metals, trace elements, etc. may suppress the immune system of fish leading to increased susceptibility to infectious diseases and thereby leading to mortality. In addition, the infected fish from such sources may sometimes become public health hazard. The present study was carried out in Ludhiana city of Punjab state and the water samples were collected from a nallah (brook) known to be contaminated with waste from industries and sewage.
In this study, the water samples showed high concentrations (in mg/L) of all the 8 heavy metals investigated iron (35.86), zinc (2.75), manganese (0.166), nickel (0.090). chromium (0.065), copper (0.045), lead (0.044) and cadmium (0.025). Common Carp fish was reared in a water tank containing polluted water from the nallah. Exposure of fish to the polluted water (3%) for 2 weeks led to sudden mortality among 60% of the tested fish. Aeromonas hydrophila and Escherichia coli were isolated from the gut of the dead fish. Thus, polluted water makes fish susceptible to microbial infections which poses a danger to public health.

Keywords: Aeromonas hydrophila, E. coli, fish disease, heavy metals, water pollution