KUALA LUMPUR: Local fish in ponds and rivers in Perak and the Klang Valley are in danger of being wiped out due to two highly aggressive predator fishes which are wreaking havoc in the waterways.

Environmentalists have raised the alarm that if the biological invasion by the carnivorous peacock bass and the zebra cichlid (both from the cichlid family) is not checked, it will cause havoc on biodiversity and the livelihood of riverine fishermen.

Where these two predator fish are found, they have moved to the top of the fish chain, even attacking the original "king" of Malaysian predator fish, the toman.

And that is why local fishermen are hauling in fewer toman, haruan, sebarau and udang galah.

These predator fish attack in groups and their prey are known to beach themselves in futile attempts to escape being eaten.

DHI Water and Environment Sdn Bhd environmental consultant Mohd Zambri Mohd Akhir is particularly concerned about the threat posed by the peacock bass.

"Now you can find these fish in Chenderoh, the most downstream dam in Perak. If it enters the other river systems in Malaysia that has unique local species, it is going to cause irreversible damage," warned Zambri.

He said the peacock bass was already robbing riverine fishermen of their livelihood as the problem had been around for nearly a decade.

"Fishermen in Batu Gajah and Tanjung Tualang are already facing this problem as their income has been steadily suffering over the years.

"The supply of udang galah is also greatly reduced, depriving fishermen of a decent income."

The peacock bass is from the Amazon in South America and can grow up to five kilogrammes. It breeds fast and protects its eggs and fry, giving it a high survival rate.

The zebra cichlid from Africa, however, only grows up to palm size, but is known for its notorious feeding habits.

Fisherman Ishanorzaman Jaimit from Kampung Gajah confirmed that there were many peacock bass in the mining ponds and rivers in Perak, but said that they only ate the small fish.

There is also increasing demand for the peacock bass. Fishermen get  RM5 per kg for it, while the middlemen sell it for RM6.50 per kg.

The peacock bass is not usually available in restaurants but it is known to make it to the dinner tables of fishermen and anglers who catch it.

Vincent Chin, owner of the Malaysian Fishing Net website, however, insists that the peacock bass is a real threat.

"It was brought into the country as an aquarium fish more than 10 years ago. It is a real nuisance because it feeds on local fish. They are vicious and attack like a pack of wolves," he said.

Another riverine fisherman, Muhammad Isa, said the zebra cichlid, nicknamed ikan belang for its distinctive stripes, was a bigger threat.

"The zebra cichlid is a bigger threat to the local species than the peacock bass," he said.

"In rivers and ponds in my area, the peacock bass is noted for eating only the perimpin (freshwater version of the ikan bilis).

"The zebra cichlid, however, eats most fry. Even if we haul in these zebra cichlids, we do not eat them."