Durgam Cheruvu fish deaths linked to oxygen depletion, pollution
HYDERABAD: Hundreds of fish have died at Durgam Cheruvu due to severe oxygen depletion linked to high organic and nutrient pollution, according to Telangana Pollution Control Board (TGPCB) data released in May 2026, as reported by DC.
The lake recorded dissolved oxygen (DO) of just 0.3 mg/l. This is far below the Central Pollution Control Board (CPCB) minimum of 4 mg/l for fisheries. Healthy fish habitats usually maintain DO levels of 5 mg/l or more.
The chemical oxygen demand (COD) stood at 123 mg/l. This points to a high load of oxidisable substances in the water. The biochemical oxygen demand (BOD) was 12 mg/l. That is six times the Class A limit and four times the Class B and C limits set by the CPCB.
High BOD means microorganisms use up oxygen as they break down organic matter. This can leave too little oxygen for fish and other aquatic life.
The nutrient levels also point to a risk of eutrophication. Excess nutrients can trigger rapid algal growth. Total phosphate stood at 0.91 mg/l, while orthophosphate was 0.83 mg/l.
Excess phosphorus can fuel algal blooms. When algae die and decompose, microorganisms consume oxygen. This can further reduce oxygen levels and harm aquatic life.
Environmental scientist Srikanth Rao said mass fish deaths rarely have a single cause.
“Mass fish deaths mostly happen when a collective system goes wrong. Cutting off sewerage inflows must be the first step. Continuous monitoring of DO, BOD, COD, ammonia and nutrients is essential,” he said.
Rao said aeration could offer short-term relief. However, he stressed that authorities must stop pollutants from entering the lake and restore its ecological balance for a lasting solution.
