Thousands of milk fish float in a cage after a massive fish kill at Taal Lake in Talisay, Batangas, south of Manila May 29, 2011. [Photo/Agencies]

TALISAY, Philippines - More than 800 tons of fish have died and rotted on a fish farm near Manila that Philippine authorities are blaming on a sudden temperature drop.

Government fisheries official Rose del Mundo said Sunday that the die-off started last week in Lake Taal in Batangas province but has eased.

The surface of the lake in the areas cordoned off for farming is packed with rotting milkfish. Milkfish are a common part of the Philippine diet.

Del Mundo says an initial investigation showed the deaths may have been caused by the temperature change as the rainy season set in after a scorching summer, which had also depleted the lake's oxygen levels.

Officials say they have banned the sale of the rotting fish, which are being buried by the truckload.