Puchong, Malaysia – On a current Sunday morning, a couple of dozen males with fishing nets skirted the rubbish-strewn banks of the Klang River simply outdoors the Malaysian capital of Kuala Lumpur.
Surveying the river, the boys solid their nets into the polluted water. The nets billowed open and sunk rapidly underneath the load of steel chains.
From the place they stood on the riverbank, they began to tug of their nets, already stuffed with dozens of squirming black-bodied catfish.
“You don’t see every other fish. Solely these,” stated Mohamad Haziq A Rahman, the chief of Malaysia’s “overseas fish hunter squad”, as they emptied their catch of wriggling suckermouth catfish into piles, away from the river.
Not one of the fish caught that morning have been bought at close by markets or meals stalls. The only real objective of the expedition was to cull suckermouth catfish, one amongst a rising variety of invasive species which have in current many years dominated freshwater habitats throughout Southeast Asia.
Invasive fish hunter Mohd Nasaruddin Mohd Nasir, 44, throws his web from the banks of the Langat River in Bangi, some 25km (16 miles) south of Malaysia’s capital Kuala Lumpur, in March 2025 (Patrick Lee/Al Jazeera)
As soon as introduced in for industrial or hobbyist causes, invasive fish usually are not solely threatening to edge native species out of the meals chain in Malaysia and elsewhere, however in addition they unfold illnesses and trigger nice harm to native environments.
Invasive fish are an issue the world over, however consultants say the problem is keenly felt in mega-biodiverse Malaysia.
“Greater than 80 % of rivers within the Klang Valley have been invaded by overseas fish species, which might trigger the extinction of the rivers’ indigenous aquatic life,” stated Dr Kalithasan Kailasam, a river professional with the Malaysia-based World Atmosphere Centre.
“It’s rising in virtually all different important rivers in Malaysia,” stated Kailasam, explaining how species such because the suckermouth have the potential to rapidly reproduce and survive in soiled water, leaving native fish on the shedding facet.
Other than the suckermouth, Malaysia’s waterways are actually threatened by species such because the aggressive peacock bass, Javanese carp and redtail catfish, he stated.
Whereas the complete extent of the issue isn’t but recognized, Malaysia’s fisheries division, after a four-year research till 2024, discovered invasive species in 39 areas throughout practically each state in peninsular Malaysia and on the island of Labuan, together with in dams, lakes and main rivers.
Alarmed by the menace, a small group of residents banded collectively to battle the aquatic invaders.
Led by Haziq, they’re working to reclaim Malaysia’s rivers one fin at a time.
Mohamad Haziq A. Rahman, centre left, founding father of Malaysia’s overseas fish hunter squad, holds a suckermouth catfish simply caught from the Klang River, as he information a social media video for his on-line followers in Puchong, Malaysia, February 2025 (Patrick Lee/Al Jazeera)
Invasive fish invasion
The citizen fish hunters’ quest to battle invasive species began in the course of the nation’s COVID-19 lockdowns, when Haziq, a former healthcare advisor, turned to fishing as a pastime in a river close to his home in central Selangor state. He discovered each fish he caught was of the suckermouth selection, also referred to as the “pleco” or “ikan bandaraya” – which interprets because the “janitor fish” in Malay and is favoured by hobbyists to maintain aquariums clear, because the suckermouth feeds on algae, leftover meals and lifeless fish.
Native to South America, styles of the suckermouth have additionally been launched into waterways in america, Bangladesh, and Sri Lanka, usually when homeowners dump them into rivers, canals, dams or free them after they develop too massive for his or her aquarium tanks.
Due to their thick, scaly pores and skin, suckermouths are normally averted by even bigger predators in Malaysia, and may develop to about half a metre (1.6ft) in size.
As backside feeders, the catfish have been recognized to eat the eggs of different species and destroy their nesting websites. Catfish additionally burrow into riverbanks to nest, inflicting them to erode and collapse, which is a severe environmental challenge in flood-prone Malaysia the place year-end monsoon winds carry heavy rain.
A lady holds up a suckermouth catfish simply caught from the Klang River in Puchong, Malaysia, in February 2025 (Patrick Lee/Al Jazeera)
Malaysia’s central financial institution stated in 2024 that floods are the reason for 85 % of the nation’s pure disasters, with their frequency rising since 2020.
Although removed from his favorite fish to catch, Haziq found that suckerfish roe could possibly be used as bait for different greater fish, and he earned some cash promoting their eggs to different fishing fans. He additionally gained a following by placing his exploits on social media. Additional analysis then led him to study concerning the threats posed by invasive species.
Haziq began to draw like-minded anglers, and, in 2022, they determined to kind a bunch for searching suckermouth, assembly practically each week in a river to hold out a cull.
Their public profile and recognition are rising. The group’s membership has now grown to greater than 1,000, and it has a powerful fan following on social media.
“Individuals stored asking methods to be part of our group, as a result of we have been trying on the ecosystem,” Haziq stated.
Focusing first on Malaysia’s Selangor state and rivers within the capital Kuala Lumpur, the fish hunter squad had netted practically 31 tonnes of suckermouths by 2024. They’ve additionally visited rivers in different states in Malaysia as their marketing campaign expands.
Muhammad Syafi Haziq, a member of the fish hunters, holds a full web’s value of suckermouth catfish only recently netted from the Klang River in Puchong, Malaysia (Patrick Lee/Al Jazeera)
Dispose, use for analysis, or prepare dinner and eat?
Throughout a hunt within the Klang River earlier this 12 months, Haziq and his comrades deployed to the river’s banks on a mission to see what number of suckermouth they may catch throughout a single outing.
However trying to find invasive fish will be difficult. With out boats, the hunters need to wade into the fast-moving polluted waters from muddy banks, whereas navigating underwater particles corresponding to garbage on the riverbed.
Nearly all of the fish they caught have been of the invasive variety, however every now and then, they do web an area.
“Haruan (snakehead)!” shouted ex-navy diver Syuhaily Hasibullah, 46, as he confirmed off a small fish half the scale of his arm, taken from a web containing a number of suckermouths.
“This one is uncommon! There was once a number of them within the river,” he informed Al Jazeera.
Haziq stated if the hunters discovered many invasive species of their nets, they’d organise one other outing to the identical location, bringing alongside extra folks to participate.
The day they got down to calculate what number of invasive fish they may catch in a single outing turned out to yield half a tonne of suckermouth in simply three hours – so many they needed to stuff them into sacks.
Beforehand, the hunters buried their hauls in deep holes away from the river. Now, they’ve discovered extra inventive methods to dispose of what’s, typically, an undesirable fish.
On the occasion earlier this 12 months, sacks of suckermouths have been handed over to an area entrepreneur seeking to experiment with turning the fish right into a type of charcoal often called biochar.
Some native universities have additionally began researching the doable use of the suckermouth. One college analysis article explored the potential of suckermouth collagen for pharmaceutical use, whereas one other thought of its use as fertiliser and even as a sort of leather-based.
On some events, the hunters even eat the fish they catch, although that depends upon which river they’ve been taken from.
Skewers of suckermouth catfish in satay being grilled by a riverbank in March 2025 (Patrick Lee/Al Jazeera)
Whereas redtail or African catfish are thought of delicacies by some, the suckermouth, additionally recognized in India as “satan fish”, is a much less enticing snacking choice – however not out of the query in the case of a fast riverside grill.
“If the fish is from the Klang River, we don’t eat it,” Mohd Zulkifli Mokhtar informed Al Jazeera, earlier than dozens of hunters broke their quick in the course of the holy Muslim month of Ramadan.
“But when it’s from the Langat River, it’s nonetheless OK,” Zulkifli stated, as dozens of suckermouth caught within the much less polluted Langat River, situated in Bangi some 25km (16 miles) south of Kuala Lumpur, have been gutted, marinated in satay and grilled on skewers.
Research from Bangladesh and Indonesia have discovered styles of catfish with excessive ranges of heavy metals and contaminants. A 2024 article by Malaysia’s Universiti Teknologi Mara cited a research that confirmed the extent of contaminants within the suckermouth was “closely influenced by the extent of air pollution within the river”.
‘If we don’t act now, it could be worse’
Whereas Malaysia’s fisheries division stated there have been no information of native species turning into endangered due to invasive ones, native fish nonetheless face threats.
Native fish both confronted turning into prey or have needed to battle to outlive, with the division discovering in a survey that 90 % of the fish in six rivers within the Selangor and Kuala Lumpur area have been now overseas arrivals.
The division’s Director-Common Adnan Hussain stated numerous measures had been put in place, together with the discharge of some 33.6 million native fish and prawns into rivers nationwide from 2021 to 2025 to “stability the influence” of invasive fish.
Late final 12 months, the state authorities of Selangor additionally got here up with a scheme to pay anglers one Malaysian ringgit ($0.23) for each kilogramme (2.2lb) of the suckermouth fish faraway from two rivers. The captured fish have been to be became animal feed and natural fertiliser, an official stated.
A person guts a suckermouth catfish just lately caught within the Langat River throughout a hunt for invasive species in March 2025 (Patrick Lee/Al Jazeera)
Restrictions on the import of sure overseas aquatic species – together with total species and teams – into Malaysia have been additionally imposed final 12 months, and the fisheries division stated that programmes and collaboration with the fish hunters had additionally helped to take care of the issue.
In a single river in Selangor state, Adnan stated the quantity of invasive fish caught following one eradication programme had dropped from 600kg (1,300lb) in a Might 2024 occasion to simply greater than 150kg (330lb) 4 or 5 months later.
Nonetheless, Universiti Malaysia Terengganu fish researcher Professor Amirrudin Ahmad stated it was “virtually not possible” to totally exterminate the nation’s invasive fish.
“So many species dwell in (native water our bodies) and eliminating invasive species by the technique of poisoning the water isn’t possible in any respect,” he stated, including there have been near 80 recorded fish species launched in Malaysia to date.
He additional warned that rising temperatures brought on by local weather change could even enable species just like the predatory Mekong redtail catfish to proliferate in cooler upstream waters in Malaysia.
“They’re right here to remain,” Amirrudin stated.
“It’s merely,” he stated, “that the atmosphere is generally just like their native nation, or these species are extremely adaptable.”
That that is an ecological battle that may by no means really be gained is some extent that Haziq and his fellow fish hunters are totally conscious of. Almost each river they visited in current occasions had virtually nothing however invasive fish, he stated.
However their mission will keep on, he added, together with the searching and public consciousness that has spurred 1000’s to observe his social media movies on the topic.
“Sure, this fish gained’t be utterly gone from our rivers,” he informed Al Jazeera.
“But when we don’t act now, it could be worse,” he stated.
“It’s higher to take motion than to simply go away it alone,” he added.
“No less than we will cut back the inhabitants, than enable it to utterly take over our native fish.”
