KUALA TERENGGANU: Ichthyologists, researchers and fishermen want the government to take a more serious look at the threat of monstrous predatory fishes that have invaded major rivers and are endangering indigenous species.
They said fish, such as the Mekong red tail catfish (Hemibagrus wyckioides), which originates from the Mekong River, and the peacock bass (Cichla ocellaris) from the Amazon River, are devouring local species and may force some into extinction.
Anglers along Sungai Pahang have also landed the red tail catfish species (Phractocephalus hemioliopterus), which originates from the Amazon River. The fish, which can grow up to 1.8m long and weigh more than 80kg, has little commercial value as food.
Hamzah Deris, 47, a fisherman from Temerloh, said the Mekong red tail catfish had become a regular catch among fishermen and its gigantic size suggested that it had been devouring local fish in Sungai Pahang.
“It is edible. It looks like the more favoured baung (Mystus spp), but the red tail differentiates both species.
“I have been catching more and much bigger Mekong red tail catfish. I am worried about the future of fishermen as well as the local species,” he said.
“I first caught the Mekong red tail catfish three years ago, and have since caught bigger ones. I was told it can grow up to more than a metre long and weigh more than 80kg. Who is going to buy such a giant fish? And it is not even favoured by locals.”
Hamzah said he believed the Mekong red tail catfish had escaped from an aquaculture farm run by Cambodian immigrants living along Sungai Pahang, somewhere near Pekan.
“I heard their fish cages were damaged by logs and other debris from upstream. All the red tail catfish escaped,” he said, adding that anglers also landed another catfish species from the Amazon River, identified as Phractocephalus hemioliopterus.
“It is a beautiful catfish with black markings on its body and red fins. Unfortunately, no one wants to buy this fish because of its black flesh. It is good for aquariums when small, but becomes a nuisance when it outgrows the aquarium.”
Zahari Zaidi, 44, another fisherman from Temerloh, said the invasion of the Mekong red tail catfish had reached an alarming level. To prove his point, he set a gill net in the river for 30 minutes, and before long, landed a number of the fish.
“It is becoming a serious problem for fishermen. I fear species like tengalan (Puntioplites bulu), jenkua (Labeo chrysophekadion) and baung will become extinct when the Mekong red tail catfish multiplies,” he said.
Angler Mohd Hairulanuar Arrifin, 35, said over the past one year, he had landed the Mekong red tail catfish more frequently in Sungai Pahang,
“If I catch 10 fish, two will be red tail catfish. The species is in high demand from restaurant operators,” he said, adding that the red tail catfish had invaded most parts of Sungai Pahang.
“The red tail fetches about RM40 per kilo. The flesh is much more delicate and soft, which makes it a popular menu at restaurants, even rivalling the local ikan patin,” he said.
Hairulanuar said the red tail catfish ate prawns and smaller baung in Sungai Pahang. He was, however, unsure if the species could pose a threat to other species.
Ichthyologist Mohd Ilham Norhakim Lokman, 32, said most major rivers in Malaysia had become hosts to predatory species, such as the Mekong red tail catfish, Chao Phraya high fin giant catfish, pirarucu, alligator gar and peacock bass.
“These are giant fishes and they have a big appetite. They will eat fish of any size. They are nice to raise as pets when small but become unmanageable when they outgrow the aquarium.
“But releasing predatory fish into a river is a big mistake.
“Everyone knows how big some predatory fish from the Amazon River can become,” he said.
“I hope some universities or the Fisheries Department can conduct research on the invasion of these predatory species and take action, including tightening the law, before it is too late.”
Pahang Fisheries Department director Azahari Othman said the department had never encouraged cage fish farmers to rear the red tail catfish as it is a predatory fish.
“The fish can disrupt the eco-system in river, especially when its population grows. It is an aggressive species that eats tiny fish fry and prawns.
“People rear the fish due to its demand from restaurants operators.
“Some aquaculture farms in Pekan rear the fish and the species might have escaped into Sungai Pahang during major floods several years ago.”
Azahari said the department hoped to conduct a study on the red tail catfish species to check if it threatened the survival of local species.
“We want to dissect the red tail catfish and study its stomach contents. This will give us an indication of its eating behaviour.”