SALEM: Thousands of fish were found dead and floating in the 16-Gate canal of Mettur Dam in Salem on Wednesday, causing concern among residents and local fishermen. The incident occurred after the release of surplus water through the canal was stopped earlier this week, leaving water stagnant along the stretch.
Fishermen from the nearby hamlets, who had been casting nets in the canal for the past two days, began collecting the dead fish using cast nets and selling them to the public. The practice triggered alarm, who feared the fish might be unsafe for consumption.
Responding to the incident, the Fisheries Department conducted an inspection and collected water samples for testing. According to the department’s report, the dissolved oxygen level in the canal water was found to be extremely low, around 1.5 mg/l, far below the required 3- 5 mg/l needed to sustain aquatic life. The condition led to suffocation and subsequent death of fish, particularly larger species such as katla, mirgal, and rohu.
“We carried out an immediate inspection on receiving information. We collected water samples from four different places and sent them for testing. The test results showed that the water had a temperature of 28 degrees Celsius and low oxygen levels that were not enough to sustain aquatic life. The sudden stoppage of surplus water also contributed to the depletion of oxygen. There were no traces of intoxication,” said Uma Kalaiselvi, Assistant Director of Fisheries, Mettur.
Officials concluded that the mass fish mortality was most likely caused by oxygen depletion resulting from stagnant water, reduced inflow after the stoppage of surplus discharge, and high ambient temperature. The report also noted the absence of toxic residues or chemical pollutants in the collected samples.