Malaysia’s ‘fish hunters’ target invasive species, one catch at a time | Environment News

Puchong, Malaysia – On a latest Sunday morning, a few dozen males with fishing nets skirted the rubbish-strewn banks of the Klang River simply exterior the Malaysian capital of Kuala Lumpur.

Surveying the river, the boys forged their nets into the polluted water. The nets billowed open and sunk rapidly below the burden of metallic chains.

From the place they stood on the riverbank, they began to drag of their nets, already full of dozens of squirming black-bodied catfish.

“You don’t see some other fish. Solely these,” mentioned Mohamad Haziq A Rahman, the chief of Malaysia’s “international 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 offered at close by markets or meals stalls. The only real function of the expedition was to cull suckermouth catfish, one amongst a rising variety of invasive species which have in latest a long time dominated freshwater habitats throughout Southeast Asia.

As soon as introduced in for business 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 ailments and trigger nice injury to native environments.

Invasive fish are an issue the world over, however specialists say the difficulty is keenly felt in mega-biodiverse Malaysia.

“Greater than 80 % of rivers within the Klang Valley have been invaded by international fish species, which might trigger the extinction of the rivers’ indigenous aquatic life,” mentioned Dr Kalithasan Kailasam, a river knowledgeable with the Malaysia-based World Surroundings Centre.

“It’s rising in virtually all different most important rivers in Malaysia,” mentioned Kailasam, explaining how species such because the suckermouth have the potential to rapidly reproduce and survive in soiled water, leaving native fish on the dropping aspect.

Other than the suckermouth, Malaysia’s waterways are actually threatened by species such because the aggressive peacock bass, Javanese carp and redtail catfish, he mentioned.

Whereas the total extent of the issue will not be but identified, Malaysia’s fisheries division, after a four-year research till 2024, discovered invasive species in 39 areas throughout almost each state in peninsular Malaysia and on the island of Labuan, together with in dams, lakes and main rivers.

Alarmed by the risk, a small group of residents banded collectively to struggle the aquatic invaders.

Led by Haziq, they’re working to reclaim Malaysia’s rivers one fin at a time.

Invasive fish invasion

The citizen fish hunters’ quest to struggle 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, forms of the suckermouth have additionally been launched into waterways in the USA, Bangladesh, and Sri Lanka, usually when homeowners dump them into rivers, canals, dams or free them after they develop too giant for his or her aquarium tanks.

Due to their thick, scaly pores and skin, suckermouths are often 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 identified 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 difficulty in flood-prone Malaysia the place year-end monsoon winds convey heavy rain.

Malaysia’s central financial institution mentioned 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 may very well be used as bait for different greater fish, and he earned some cash promoting their eggs to different fishing lovers. 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 gaggle for searching suckermouth, assembly almost 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 robust fan following on social media.

“Individuals saved asking learn how to be a part of our group, as a result of we have been wanting on the ecosystem,” Haziq mentioned.

Focusing first on Malaysia’s Selangor state and rivers within the capital Kuala Lumpur, the fish hunter squad had netted almost 31 tonnes of suckermouths by 2024. They’ve additionally visited rivers in different states in Malaysia as their marketing campaign expands.

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 attempting to find invasive fish might be tough. With out boats, the hunters need to wade into the fast-moving polluted waters from muddy banks, whereas navigating underwater particles akin to garbage on the riverbed.

Nearly all of the fish they caught have been of the invasive type, however infrequently, they do web a neighborhood.

“Haruan (snakehead)!” shouted ex-navy diver Syuhaily Hasibullah, 46, as he confirmed off a small fish half the dimensions of his arm, taken from a web containing a number of suckermouths.

“This one is uncommon! There was once numerous them within the river,” he advised Al Jazeera.

Haziq mentioned if the hunters discovered many invasive species of their nets, they might organise one other outing to the identical location, bringing alongside extra individuals 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, usually, an undesirable fish.

On the occasion earlier this 12 months, sacks of suckermouths have been handed over to a neighborhood entrepreneur trying to experiment with turning the fish right into a type of charcoal often called biochar.

Some native universities have additionally began researching the potential use of the suckermouth. One college analysis article explored the potential of suckermouth collagen for pharmaceutical use, whereas one other thought-about its use as fertiliser and even as a kind of leather-based.

On some events, the hunters even eat the fish they catch, although that is determined by which river they’ve been taken from.

Whereas redtail or African catfish are thought-about delicacies by some, the suckermouth, additionally identified in India as “satan fish”, is a much less engaging snacking possibility – 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 advised 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 mentioned, as dozens of suckermouth caught within the much less polluted Langat River, positioned 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 forms 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 mentioned there have been no data 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 struggle 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 international arrivals.

The division’s Director-Common Adnan Hussain mentioned 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 “steadiness 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 mentioned.

Restrictions on the import of sure international aquatic species – together with total species and teams – into Malaysia have been additionally imposed final 12 months, and he added 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 mentioned the quantity of invasive fish caught following one eradication programme had dropped from 600kg (1,300lb) in a Could 2024 occasion to only greater than 150kg (330lb) 4 or 5 months later.

Nonetheless, Universiti Malaysia Terengganu fish researcher Professor Amirrudin Ahmad mentioned it was “virtually unimaginable” to completely exterminate the nation’s invasive fish.

“So many species reside in (native water our bodies) and eliminating invasive species by the technique of poisoning the water will not be possible in any respect,” he mentioned, including there have been near 80 recorded fish species launched in Malaysia thus far.

He additional warned that rising temperatures attributable to 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 mentioned.

“It’s merely,” he mentioned, “that the atmosphere is usually much like their native nation, or these species are extremely adaptable.”

That that is an ecological struggle that may by no means really be received is a degree that Haziq and his fellow fish hunters are totally conscious of. Practically each river they visited in latest occasions had virtually nothing however invasive fish, he mentioned.

However their mission will stick with it, he added, together with the searching and public consciousness that has spurred hundreds to comply with his social media movies on the topic.

“Sure, this fish received’t be utterly gone from our rivers,” he advised Al Jazeera.

“But when we don’t act now, it could be worse,” he mentioned.

“It’s higher to take motion than to only go away it alone,” he added.

“At the very least we are able to scale back the inhabitants, than enable it to utterly take over our native fish.”