Officials from the fisheries department and Kolkata Municipal Development Authority (KMDA) collected water samples from Rabindra Sarobar on Monday to find out whether any drastic change in the water's properties was causing the death of fish.
Over the past few days, morning walkers and guards have been noticing dead fish floating in different corners of the water body.
“The pollution control board regularly monitors the water of Rabindra Sarobar. We want to check whether the change was induced by pollution caused by run-off following the heavy rain in September,” said an official of the KMDA, the custodian of the south Kolkata water body.
Scientists said fish die in large numbers when the dissolved oxygen content of the water falls below the safe level.
“The death of one or two animals does not usually signal a fall in the oxygen level…. But many dead fish have been spotted in the lake,” a pollution control board scientist said.