‘Monster fish’ in polluted Pasig River explained

Kristine Sabillo, ABS-CBN News

Posted at Sep 06 2019 01:19 PM | Updated as of Sep 06 2019 04:57 PM

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Vic Herrera has been fishing in Pasig River since the late 1970s. He knows the ebb and flow of the once biologically dead river, which he said “dies” or becomes foul-smelling during summers.

In the months that it is alive and infused by rainwater and the Laguna Lake, the 58-year-old vendor brings out his fishing rod in search of tilapia.

“Malinis pa ito (noong 1977),” Herrera says. “Biya, talangka, hipon at saka gurami. Maraming isda dito nu’ng ’70s. Mababaw ’yan, kita mo pa ang buhangin d’yan. May mga tulya dito noong araw.”

(It used to be clean in 1977. There were gobies, crabs, shrimp and gourami. There were a lot of fish here in the ’70s. The river was still shallow and you could see the sandy bottom. There were also clams.)

‘Monster fish’ in polluted Pasig River explained 1
Vendor Vic Herrera shows off his catch for the day, as he pursues his fishing hobby in Pasig River. Mark Demayo, ABS-CBN News

In the 1990s, Pasig River was declared biologically dead because of extreme water pollution that made it impossible for living organisms to thrive in.

Herrera points to a warehouse with dark water-filled pipes draining into the river. That’s one of the culprits, he says, referring to industrial waste that continues to pollute Pasig River.

But as the river is continuously rehabilitated by government and volunteer organizations, various fish species have been spotted again.

In fact, the fish in Pasig River have been making headlines as local fishermen boast of catching “giant,” “monster” fish including a“catfish-zilla.”

Herrera says locals are delighted by the presence of larger fish, such as cream dory, catfish and tilapia, especially since fishing has become a form of recreation in their community.

When ABS-CBN News visited one Thursday, Herrera catches four small catfish (kanduli) with his worm bait. It is a small catch compared to a month ago when they were catching big tilapia.

‘Monster fish’ in polluted Pasig River explained 2
Vendor Vic Herrera catches two pieces of kanduli in Pasig River. Mark Demayo, ABS-CBN News

He points to another fisherman, Aldrin Mahinay, who recently caught a cream dory nearly the size of a child.

Mahinay, 58, is not as fortunate that day. He catches a janitor fish as large as his forearm but returns it into the water because it is not edible. Instead, he shows photos and videos of his biggest catch this year: a 20-kilo cream dory.

His secret weapon? A sturdy fishing rod with four large hooks. He doesn’t use bait but instead cast the hook-laden line into the murky river, betting on the possibility that one or two large fish would eventually swim into his hooks.

“Ang isda tumatalon sa ilog. Marami. Kahit ito walang pain hahagisan lang namin,” he says.

(We can see the fish jump in the river. A lot of them. We don’t need bait. We just cast our lines.)

‘Monster fish’ in polluted Pasig River explained 3
Retired jeepney driver Aldrin Mahinay spends hours in Pasig River to catch large cream dory fish. Mark Demayo, ABS-CBN News

“It takes three or four hours to catch a big one,” he tells ABS-CBN News. Sometimes he eats his catch with the other locals, other times, he sells the cream dory for P60 a kilo. His regular catch? Around seven to 20 kilos a day.

“Ngayon kasi malinis na ang ilog. Hindi tulad ng dati na madumi s’ya,” he says.

(Now the river is clean. Unlike before when it was very dirty.)

But is it really clean?


Not really, according to the Pasig River Rehabilitation Commission (PRRC).

Last July, the PRRC announced that fish caught from the river this year still contained fecal coliform and heavy metals.

Fecal coliform or waste coming from humans or animals were at 14 to 2,400 MPN (most probable number) per gram in different areas of the river compared to the standard of 10 MPN/gram.

The PRRC says that areas with extremely high levels of fecal coliform had poultry and other businesses surrounding it.

Other areas also had high levels of lead and mercury in the water.

In particular, a three-kilogram tilapia caught last July tested positive for Chromium VI, a toxic heavy metal.

While the fecal coliform levels are actually an improvement compared to a few decades ago, the water in Pasig River is still not safe for humans.

“According to studies done by experts, the fish is not safe to eat yet,” PRRC executive director Jose Antonio Goitia tells ABS-CBN News.

He says that while Pasig River has been improving because of the relocation of houses beside it, it has yet to achieve a Class C rating, which is given to bodies of freshwater that can be used for boating, fishing and agriculture.


Asked if they are worried about the PRRC’s findings, Herrera and Mahinay say they do not think there is anything wrong since nothing has happened to them after eating the fish.

At the nearby market, Virgilio Carogda and his brother sell fish from Navotas but eat their own catch from Pasig River.

“Kung merong deperensya and isa sa blog na ’yan siguro nagkakasakit kami. Fifty-three na ako,” says Carogda, who denies they are selling the Pasig River fish in the market.

(If there was anything wrong with the fish in the river then I should have gotten sick. I’m 53 already.)

‘Monster fish’ in polluted Pasig River explained 4
Fish vendor Virgilio Carogda insists the fish from Pasig River is safe to eat. However, he denies selling it at the market. Instead, they buy fish from the Navotas fish port. Mark Demayo, ABS-CBN News

Like Herrera, Carogda has been fishing in Pasig River for decades. “It is relaxing,” he says, recalling how they used to catch biya (gobies), ayunging (silver perch), dalag (mudfish), hito (catfish) and even bangus (milkfish).


While the PRRC acknowledges that cleaner waters should be credited for the proliferation of fish in the river, experts believe that this is only because the species present are used to polluted waters.

“The fish in Pasig River are highly tolerant to pollution levels,” says Dr. Luis Garcia, a professor at University of the Philippines specializing in aquaculture and fish physiology. Among his examples are tilapia, big head carp (Imelda) and kanduli.

He says these fish are resilient species from other countries that are able to survive in waters with low oxygen levels.

While it is true that water in Pasig River is replenished through the water cycle and Laguna Lake during the rainy season, Garcia points out that it remains polluted because of the continuous throwing of wastewater into the system.

He says the most probable reason why the fish are able to grow that big is because they are “escapist” fish from Laguna Lake.

“They escaped fish pens in Laguna Lake and were not immediately caught so they have enough time to reach that size,” Garcia says.

Cream dory and tilapia are usually not allowed to get that large and are harvested from fish pens as soon as they reach adult size.

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Dr. Benjamin Vallejo, who is also a professor at University of the Philippines specializing in marine biology, says that the fish found in Pasig River now are invasive species. These are fish from other countries that were introduced to the Philippines decades ago to boost fisheries.

But because they are resilient or easy to grow, they also tend to destroy or cause imbalance in the ecosystem, pushing away other fish species.

Vallejo says the native fish species that used to thrive in Pasig River can no longer be found there. Some of them were mentioned in Jose Rizal’s novel “Noli Me Tángere”. In one passage, Rizal mentions how Filipinos would catch ayungin, biya, dalag, buwan-buwan, and banac from the river to cook.

“Among the foreign fish introduced in our waters in the 1960s was tilapia (from Africa),” Vallejo says. “We also have Imelda or big head carp introduced (by first lady Imelda Marcos) from China . . . even grass carp from Thailand.”

“They are more adapted to polluted water conditions. Number one example there is the janitor fish,” he says.

For a while, the population of the janitor fish in Pasig and Marikina got so out of hand that Vallejo and other experts were called upon by the local governments to conduct a study. Vallejo says that if authorities can’t catch the invasive species in large numbers, they will have to wait until the river becomes clean.

Today, there are still large janitor fish in Pasig River, in sizes that are a hundred times bigger than the ones placed in aquariums.

While Garcia and Vallejo think there is nothing unusual or incredible in the large fish that are being caught in Pasig River, they worry because the situation shows how much invasive species have dominated the once thriving body of water.

‘Monster fish’ in polluted Pasig River explained 5
Pasig River Rehabilitation Commission executive director Jose Antonio Goitia looks over their masterplan for the urban communities around the historic river. Photo by Mark Demayo, ABS-CBN News


Garcia says the insistence of local residents to eat the fish in the polluted river will only result in long-term illnesses.

He says it’s different from food poisoning where you immediately see the effects.

“If you always eat contaminated fish, it will accumulate in your body. You can become barren or sterile. Your mental abilities can slow down. You won’t die immediately (but it will have an effect) and can lead to your death,” Garcia says.

The two experts say the fish that have high levels of metal and fecal coliform will remain contaminated until they die. Local residents can only eat fish born into a Pasig River that is clean.

“Only until the time we can stop dumping waste (in Pasig river),” he said.

However, the PRRC says it will take several years before the river is fully rehabilitated, which includes the comprehensive sewage treatment system.

PRRC’s Goitia says besides industries, they will have to ask for the help of the local residents themselves, especially since long-term plans include relocating communities and turning the riverbanks into esplanades with greenery.

As for fish vendor Carogda, he can only wish for the day when Pasig River is again teeming with fish that Filipinos can eat.