PETALING JAYA: At least six invasive ornamental fish species are seriously damaging the local ecosystems.
Between 2021 and 2025, more than 100 tonnes of invasive fish have been removed from Malaysian water bodies, but that has hardly made a dent in the invasion.
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“The issue has reached a critical level. What people think is an act of kindness – releasing unwanted aquarium fish into rivers or lakes – has instead allowed dozens of foreign species to breed and dominate local habitats,” says Fisheries Department director-general Datuk Adnan Hussain (pic).
At least six rivers and lakes nationwide are already affected by invasive species. These include Sungai Klang and Sungai Langat in Selangor; Tasik Temenggor in Perak; Tasik Merah in Perak, which is also in a critical state due to the presence of peacock bass, as well as several water bodies in Perlis and Johor where foreign fish are increasingly dominating local ecosystems.
Among the main culprits are the suckermouth catfish (ikan bandaraya), peacock bass (ikan raja), African catfish (ikan keli Afrika), Midas cichlid (ikan midas), Mayan cichlid (ikan mayan) and redtail catfish (baung ekor merah).
Efforts to control the problem have been extensive. Between 2021 and 2025, the department carried out 37 removal programmes nationwide, extracting 19.6 metric tonnes of invasive fish, while non-governmental organisations removed a further 84.52 tonnes.
Yet, the ecological impact remains severe.
“The suckermouth catfish is among the most destructive, with populations reaching millions in major rivers,” said Adnan.
He said the species not only feeds on the eggs of native fish but also burrows into riverbanks to build nests, weakening soil structures and triggering serious erosion.
Equally concerning is the peacock bass, an aggressive predator from the Amazon.
“It hunts native fish extensively, including species like sebarau and kelah, causing their populations to collapse,” he said.
Other species such as the African catfish out-compete native fish for food due to their rapid growth and resilience. Meanwhile, hybrid ornamental species like the blood parrot have been detected in padi fields, raising fears of disease transmission.
“What is released into the water is not just a fish, but a silent threat capable of permanently altering the entire ecosystem,” Adnan warned.
Beyond environmental damage, the issue is also affecting inland fishermen, whose catches are increasingly dominated by low-value invasive species.
To curb the problem, the Fisheries Act 1985 allows for fines of up to RM1,000, imprisonment of up to one year, or both, for those handling prohibited species without approval.
In some states like Perlis, fines can reach RM20,000 for releasing foreign fish into public waters. Authorities may also seize and dispose of the fish to prevent further contamination.
However, enforcement alone is not sufficient.
“The challenge is that these releases are often done individually and out of sight, and many still believe it is a good deed,” Adnan said.
He stressed that public awareness and responsible action are key to addressing the issue. Members of the public are urged to surrender unwanted fish to the department or a registered quarantine centre instead.
“Releasing ornamental fish into public waters is a form of biological pollution that can threaten the livelihoods of inland fishermen and destroy biodiversity,” he said.
