VIGAN CITY, Ilocos Sur, Philippines — A new fish kill happened last week on Mestizo River in Barangay Callaguip, Caoayan, Ilocos Sur, fisheries officials reported Tuesday.

Bureau of Fishery and Aquatic Resources (BFAR) Officer Benny Saraos who is based in this province reported that more than 1,000 pieces of marketable size of “tilapia,” valued around P25,000, turned up dead in Mestizo River.

“The dead fish were immediately buried upon collection from the river’s water to avoid its possible delivery for sale into the public market,” Saraos said.

He theorized that the fish kill might have been caused by decomposing waste materials that flowed into the river during heavy rains.

Such a phenomenon would produce ammonia and, thus, contaminate the river. He said samples taken from the river should high toxicity levels.

Saraos also assessed that the overcrowding of fish cages in the river aggravated the situation with the huge number of fish sharing in a limited supply of oxygen.

“At least 3 to 5 meters distance between fish cages should be maintained along the river’s water to avoid the possible suffocation of fishes along the river,” he added.

He also recommended that sonification of fish cages along the Mestizo River will be imposed through the concerned local government unit (LGU) to further anticipate the possible recurrence of a fish kill.