Ton of fish in Manila Bay dead due to ammonia

MANILA, Philippines – The deaths of a ton of fish in Manila Bay were due to high levels of ammonia, a chemical compound usually produced by dead animals and plants, said the Bureau of Fisheries and Aquatic Resources (BFAR).

The agency said on Wednesday, February 18, that it conducted an analysis of water in Manila Bay where the Philippine Coast Guard (PCG) spotted around a ton of dead fish floating in waters near the Manila Yacht Club.

The laboratory results of the physico-chemical analysis showed that the water had very high levels of ammonia, a chemical compound naturally produced by decomposing animals, plants and animal waste. The ammonia may also have come from agricultural, domestic and industrial wastes. 

The water also had low levels of dissolved oxygen which fish need to "breathe" underwater. 

The lack of dissolved oxygen and high concentration of ammonia "were the main factors that contributed to animal stress which resulted in death. Necropsy showed very dark gills, a sign of overexposure to ammonia," said the BFAR.

The agency was informed by the PCG of the incident last Monday after which it sent a Quick Response Team and Fish Health Unit personnel to investigate.

The team found around 30 to 50 kilograms of fish of different species. But a majority of the fish were mullet, locally known as banak.

On Thursday, The Manila Bay Coordinating Office (MBCO) called a meeting with BFAR and the PCG to discuss the fish mortality incident.

Filthy water quality

An ongoing mandamus is currently being implemented by various government agencies to clean up the still filthy Manila Bay. MBCO is the office created to coordinate with agencies like the BFAR, Department of Environment and Natural Resources, Department of Health, and Department of the Interior and Local Government.

While progress has been made in reducing the amount of garbage in tributary creeks and rivers in Metro Manila, the bay's water quality has not improved.

As of February 2014, it still registered coliform levels in the millions when the target coliform level (fit for swimming) is 1,000 MPN (most probable number per 100 milliliters).

In a previous interview with Manila Bay Coordinating Office chief Noel Gaerlan, he said the main reasons for deteriorating water quality are the growing population in the National Capital Region and the lack of water treatment facilities in homes and establishments around Manila Bay. 

Water concessionaires Maynilad and Manila Water are also to be blamed for not connecting all Metro Manila residents to its water treatment and sewerage lines, as they are ordered to do by the Clean Water Act.

According to the DENR, only 20 to 30% of the mega-city's residents are connected to sewerage lines of the concessionaires. 

Informal settlers living near waterways have been identified as major pollutants because they often throw their waste into creeks that drain into the bay.

Many of them also lack sanitary toilets or septic tanks with which to dispose of their excrement properly.

Despite efforts, solid waste still finds its way to Manila Bay. Green groups found plastics to be the most common type of trash in the bay.

A landmark study released last February 13 showed the Philippines was the 3rd top contributor to plastic garbage in oceans worldwide. –

Pia Ranada

Pia Ranada covers the Office of the President and Bangsamoro regional issues for Rappler. While helping out with desk duties, she also watches the environment sector and the local government of Quezon City. For tips or story suggestions, you can reach her at