Fish Kill in Mir Alam Tank, Hyderabad

http://www.hindu.com/2008/07/28/stories/2008072859000400.htm

HYDERABAD: In a rare phenomenon, hundreds of dead fish were found floating along the shoreline of Mir Alam lake from Sunday morning.

Locals, who first noticed this phenomenon, started collecting dead fish for consumption before better sense prevailed and they subsequently desisted.

All through the day, the lake shoreline was crammed with inquisitive locals, trying to witness and ‘argue’ over the reasons behind the phenomenon.

Risky affair


Hundreds of dead fish were found floating inside the phytoplankton thriving in abundance in the lake.

“I was shocked to see dead fish floating. Everyday, I venture inside on my boat to catch fish but today it was different. Even the big fish were dead and floating. Many took away several big fish before we asked them not to consume. It could be risky because the lake is polluted,” says Ali Raza, a local resident.

Residents claimed that they had never witnessed this phenomenon earlier.

“We have informed about it to zoo authorities. They asked us to contact HUDA officials. People here consume the fish and officials should clarify on the safety levels of the lake,” felt S.Q. Masood, another resident.

Wildlife experts attribute this sudden death of fish, to lack of dissolved oxygen, so vital for survival of fish. Weather conditions, especially during rainy season and cloudy days also lead to such type of problems, they say.

Decay process


A bit of rain leads to growth of plankton (microscopic plants and algae) in lakes. Planktons produce oxygen and its lifecycle is short-lived.

They die and again grow and this decay process of organic material increases consumption of oxygen, they explain.

“More organic material lead to less dissolved oxygen and without oxygen fish die,” World Wildlife Fund (WWF) State Director for Farida Tampal said.

Officials to visit site


“Cloudy conditions, rain and release of waste from naalas into the lake lead to increased consumption of oxygen. This depletion of oxygen leaves fish with less oxygen to survive. In such instances, large fish die first because they naturally need more oxygen. We will visit the place and collect water samples,” said HUDA Executive Engineer (lakes) Zafrullah Khan.

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Fish Kills can be prevented using Nualgi.