In the past few days, hundred of fish have been found dead upstream of Najafgarh drain in the South-West Delhi district.
According to the locals, scores of fish have also died in a pond in the adjoining Jhuljhuli village of the area. But the pond is not connected to the Najafgarh drain.
However, no fish was found dead in and around Najafgarh lake. The cause of the sudden deaths has not been ascertained yet.
Meanwhile, the Delhi Pollution Control Committee (DPCC) on Sunday collected samples from the drain to determine the biological oxygen demand (BOD) and the chemical oxygen demand (COD) levels of the drain.
The BOD is a measure of the amount of oxygen required for bacteria to decompose organic components present in water, while the COD measures chemicals in the water.
A local said that fish dying in the pond is beyond their understanding as it is not connected to the Najafgarh drain.
Fish can die in the drain due to the discharge of pollutants from the nearby industries.
The DPCC is looking at the matter from different angles to find out the exact cause of death.