Malaysian “fish hunter” target invasion species, catch one at a time | Environment News

Puchong, Malaysia – About 12 men with fishing nets ramped through garbage-studded banks on the Klan River just outside the Malaysian capital Kuala Lumpur.

Surveying the river, the man throws a net into the contaminated water. The net swirled and quickly sank under the weight of the metal chain.

From where they were standing on the riverbank they began to pull the nets, already filled with dozens of black-bodied catfish.

“You don’t see other fish, they’re just these,” said Rahman, the leader of Malaysia’s “foreign fish hunting squad,” and as he emptyed his catch, crumpled in the mountains far from the river, “I don’t see only other fish.”

The fish caught that morning were not sold at nearby markets or food stalls. The sole purpose of the expedition was to cull catfish in soccer trout, one of the growing numbers of invasive species that have dominated Southeast Asia’s freshwater habitats in recent decades.

Invasive fish, when brought in for commercial or enthusiast reasons, not only threatens to border native species from the food chain in Malaysia and elsewhere, they also spread disease and cause serious damage to the local environment.

Invasive fish is a problem around the world, but experts say the problem is keenly felt by the massive Malaysian creatures.

“More than 80% of the rivers in Klan Valley are invaded by foreign fish species, which can cause the extinction of indigenous aquatic species in the river,” said Dr. Kalisasan Kairasam, a river expert at the Malaysia-based Global Environment Centre.

“It grows in almost every other major river in Malaysia,” says Kairasam, explaining how seeds, such as soccer trout, can quickly replicate and survive in dirty water, leaving local fish on the losing side.

Aside from football masses, he said Malaysian waterways are now threatened by species such as aggressive peacock bass, Javanese carp and red-tailed catfish.

The full extent of the issue is still unknown, but after four years of research to 2024, the Malaysian Fisheries Division discovered invasive species in 39 regions of Labuan Island, including dams, lakes and major rivers, in 39 regions of almost every province of the Malaysian Peninsula.

Worried by the threat, a small group of citizens united in battle with the aquatic invaders.

Leading by Haziq, they work to regain one fin at a time through the rivers of Malaysia.

Invasive fish invasion

The quest for civic fish hunters to fight invasive species in the city began during the country’s Covid-19 lockdown when Hajik, a former healthcare consultant, turned to recreational fishing in the river near his home in central Selangor. He discovered that all the fish he caught were a type of soccer trout known as “pleco” or “Ikan bandaraya.” It is translated as the Malay word “manager’s fish” and is preferred for keeping the hobby clean to feed algae, remaining food and dead fish.

The varieties of soccer trout native to South America have also been introduced to waterways in the US, Bangladesh and Sri Lanka. Often, owners are released after they become too big into aquarium tanks.

Due to its thick, scaly skin, soccer trout is usually avoided by larger Malaysian predators, and can grow to about 0.6 feet (1.6 feet) in length.

As a bottom feeder, catfish are known to eat eggs of other species and destroy nesting sites. Catfish also nest on the riverbanks, nests, eroding and disintegrating. This is a serious environmental problem in Malaysia, where monsoon winds at the end of the year are prone to floods, causing heavy rain.

The Malaysia central bank said floods caused 85% of the country’s natural disasters in 2024, increasing frequency since 2020.

Although far from his favorite fish, Hazaik discovered that soccer fish rows could be used as bait for other larger fish, making money selling eggs to other fishing enthusiasts. He also gained support by placing exploits on social media. Further research subsequently taught him about the threat posed by invasive species.

Haziq began to attract like-minded anglers, and in 2022 they formed a group to hunt Suckermouth and decided to run culls on the river almost every week.

Their public profile and popularity are growing. The group’s membership has now grown to over 1,000 people and follows strong fans on social media.

“We were looking at the ecosystem, so people kept asking how to join our group,” Hazai said.

Focusing on Malaysia’s Selangor and rivers in Kuala Lumpur, the fish hunter team had won 31 tons of football by 2024. We also visited rivers in other Malaysia provinces as the campaign expanded.

Dispose of, use for research, or cooking and eating?

Earlier this year, during a hunt on the Klan River, Hazaik and his comrades deployed to the river banks to see how many football trouts can be caught during one outing.

However, hunting invasive fish can be difficult. Without a boat, hunters must walk from muddy banks to fast, polluted bodies of water, sailing through riverbed trash and other underwater debris.

Almost every fish they caught was an invasive species, but sometimes they do a local net.

“Haruan (Snakehead)!” Former Naby diver Syuhaily Hasibullah, 46, showed off a small fish half the size of his arm and filmed from the net, including several soccer trouts.

“This is rare! There used to be a lot in the river,” he told Al Jazeera.

Hazaik said that if the hunters find many invasive species in their nets, they will organize another outing to the same location and take more people.

The day they tried to calculate the number of invasive fish they could catch on a single outing, it turned out to produce 0.5 tonnes of soccer trout in just three hours.

Previously, hunters would fill the haul in deep holes away from the river. Now, they have found more creative ways to dispose of unwanted fish, generally.

At an event earlier this year, saccharmouth sachets have been handed over to local entrepreneurs, and they are about to experiment with turning the fish into the form of charcoal known as biochar.

Some local universities are beginning to investigate the potential use of soccer masses. A research article from one university examined the possibility of soccer mascolagen for drug use, while another considered its use as a type of fertilizer or leather.

In some cases, hunters will even eat fish caught, but that depends on which river they are taken from.

Redtail or African catfish are considered delicacies by some, but soccer trout, also known as “devil fish” in India, is a less attractive snack option, but it’s not a problem when it comes to Quick Riverside grills.

“If the fish are coming from the Klan River, we won’t eat it,” Maud Zurkifli Mokhtar told Al Jazeera.

“But if it comes from the Rangat River, it’s still okay,” Zulkihuli was seduced, marinated in a sateree and burned in a skewer as dozens of football trout were caught in the uncontaminated Langat River in Bangi, about 25km (16 miles) south of Kuala Lumpur.

Research in Bangladesh and Indonesia has discovered catfish species with high levels of heavy metals and pollutants. A 2024 article from the University of Technology in Malaysia cited a study showing that the levels of pollutants in soccer masses are “heavyly influenced by the levels of river pollution.”

“If we don’t act now, that would be even worse.”

Malaysia’s Fisheries Bureau said there is no record of local species being put at risk due to invasive fish, but native fish still face a threat.

Local fish had to face prey or fight to survive. In its survey, the department found that 90% of the fish in the six rivers in the Selangor and Kuala Lumpur regions are currently foreign arrivals.

Director Adnan Hussein said various measures have been introduced, including the “shock balance” of invasive fish, including the release of around 33.6 million native fish and shrimp to the rivers nationwide between 2021 and 2025.

Late last year, the Selangor government came up with a scheme to pay one Malaysian ringgit ($0.23) for every kilogram (2.2 pounds) of soccer trout fish removed from two rivers. The fish caught were to be converted to animal feed and organic fertilizer, officials said.

Restrictions on imports of certain foreign aquatic species into Malaysia, including species and groups as a whole, were also imposed last year, and the Fisheries Bureau said programs and collaborations with fish hunters have also helped address the issue.

In one river in Selangor, Adnan said the amount of invasive fish caught following one eradication programme had dropped from 600 kg (1,300 lbs) at the May 2024 event to over 150 kg (330 lbs) four or five months later.

However, Professor Amirdin Ahmad, a researcher at the University of Malaysia Telenganu Fish, said it was “nearly impossible” to completely eradicate the country’s invasive fish.

“There are so many species inhabited (natural waters), and it is absolutely impossible to remove invasive species by means of poisoning water,” he said, adding that there are nearly 80 recorded fish species introduced in Malaysia to date.

He further warned that climate change-induced temperature rises could even allow predatory Mekong Redtail catfish-like species to multiply in Malaysia’s cool upstream waters.

“They’re staying here,” Amirdin said.

“It’s simple,” he said, “the environment is almost similar to their home country, or these species are very adaptable.”

It is a point that Hazaik and his fellow fish hunters know perfectly that this is an ecological war that they can’t really win. Almost every river they visited recently had few other than invasive fish, he said.

But their mission will take over, he added, along with thousands of hunting and public awareness to follow his social media videos on the subject.

“Yes, this fish won’t disappear completely from our river,” he told Al Jazeera.

“But if we don’t act now, that would be even worse,” he said.

“It’s better to take action than just leave it alone,” he added.

“At least we can reduce our population than allowing local fish to be fully taken over.”