The initial reason of this tragic situation of dead fish on July 8 and 9 is because of heat wave, which reached more than 40 degrees Celsius in some days. Yet, on July 7, there was a sudden downpour at noon, causing an abrupt temperature change.
This has led to the death of many fish, most of which a small ones swimming near the surface of the water. They are in the breeding season and have a low stamina.
According to Mr. Nguyen Manh Hung, Head of the Division of Technical Infrastructure of the Hanoi Department of Construction, to amend this situation, the Hanoi Department of Construction has instructed related offices to increase cleaning activities on the lake by quickly collecting and treating dead fish while operating air pumps to raise the oxygen level in the lake. There were 20 tons of dead fish gathered and then handled in Nam Son Garbage Dump.