Thousands of fish were found dead on the banks of River Cauvery in and around Mettur.
Officials said reduction in oxygen level in the water led to the death of fish every year.
Thousands of fish have died and stagnated on the Cauvery river banks in Salem camp, Chinnakavur, Thangamapuripattinam, and near Sangili Muniappan Kovil over the last three days.
As the water discharged through the 16-vent surplus sluices was stopped, water stagnated like ponds and between rocks at a few places in these localities. Foul smell emanated from the dead fish at these places.
Meanwhile, local people levelled allegations against some fishermen, who used to catch fish in the river. The fishermen allegedly used explosives to catch big fish at night, which they found in the stagnant water between the rocks. Due to the vibration created by the explosives, the small fish fainted and died, the locals alleged.
Water Resources Department (WRD) officials attached to the Mettur Dam said that fish die when dissolved oxygen levels in the water are low. During every season, fish would die like this. The fish are living in the stagnated water between rocks, and while the heat increases after the rainy season, it reduces the oxygen level in the water. So, the fish cannot survive, officials said.
When asked about the fishermen using explosives to catch big fish, WRD officials said it had become difficult to nab them as they catch fish at night and no fisherman was ready to give information about people using explosives. “But, we have stepped up monitoring,” an official said.
Stating that dead fish are sent for lab tests, Fisheries Department officials said that on Friday they took a sample of water where dead fish were found. The water and dead fish were sent for lab test at the Barur Centre for Sustainable Aquaculture in Krishnagiri district, and the results are expected in two days.
According to Kolathur Block Development Office officials, the dead fish have been removed from the riverbanks at Kolnaickenpatti, and work was on in the remaining areas.
