All the SWE exposed fish appeared lethargic after exposure to the SWE compared to control fish. The major clinical symptoms such as inappetance and ataxia appeared after 2 to 3 days exposure. At higher concentrations of the SWE, the exposed fish showed erratic movement leading to collision to inner side of the aquarium. At higher exposure periods, the exposed fish appeared lethargic and irregular swimming activity was observed when compared to control fish. Fish death started in exposed aquarium after 20days of exposure. Autopsy studies revealed that the liver and brain of exposed fish were congested, pale and tender. It seems 28days of exposure to the SWE was enough for the fish not to recover 100%, showing a damage of 99.98% when compared to 28d control value and finally all the 28d exposed fish died after 22d of recovery onwards indicating permanent damage to the metabolic and biochemical systems caused by mercury. The SWE exposed fish showed paralytic movements and the body showed banding with lateral movement. The exposed fishes also showed depression in active metabolism, depletion in ventilation rate and significant decrease in whole body respiration rate. The protein content significantly decreased in brain, liver and muscle tissues of the exposed fish compared to control fish tissues. The decrease in protein content was probably due to proteolysis in exposed fish tissues. Interestingly the FAA content increased in all exposed fish tissues of the SWE exposed fish. The increase in FAA content can be correlated to either break down of protein molecules by proteolysis induced by mercury or the increase in FAA content was due to non-synthesis of protein after amino acids were produced by amino acid biosynthesis. This increase in FAA content was of no use as most of the exposed fishes to a sub-lethal concentration of SWE containing mercury killed all the exposed fish during recovery period. The depletion in protein content and increase in FAA content was due to accumulation of mercury from the environment. This fish environment was contaminated with the SWE prepared from solid waste and is almost equivalent to the lechate leaking from the solid waste dumps. Hence all care should be taken to protect the environmental segments from mercury and any other toxicant. In the present study a clear indication was available for not discharging any waste from Chlor-alkali industries in to the environmental segments.
Priyadarsan et al. (Thu,) studied this question.