KUALA TERENGGANU: The damage is done. The invasion of the Mekong red tail catfish in Malaysian rivers is irreversible. Only time will tell the fate of the indigenous fish species.
Researchers are worried that the repeated mass spawning of the red tail catfish, also known as the Asian red tail catfish, means a nearly 100 per cent fry survival rate. And in a few years, this species could occupy every available space in the rivers.
“Rivers in Malaysia are not long or wide like the Chao Phraya River or Mekong River, where the red tail catfish originates.
“This species will devour any live food, and can grow to monstrous sizes. I am worried about the future of our local species,” said Dr Amiruddin Ahmad, a senior lecturer (Ecology) at the School of Marine and Environmental Sciences, Universiti Malaysia Terengganu (UMT), in Gong Badak.
He said the best method to remove the fish was by using fishing techniques, especially baited traps. Once caught, the red tail catfish should be removed from the habitat.
“Long lines or angling is also possible. Gill netting is the least favoured as other fish species may die,” he said.
He said he believed that the giant fish had adapted to the new environment, which is not much different from its native habitat.
“With its large appetite and size, it’s easy for the fish to obtain food.
“This creates competition with local species that occupy and play a similar role in local waters, such as our ikan baung (Mystus spp).
“There isn’t much that can be done.
“We at UMT are keen to reduce, if not eliminate, this species from our water bodies.
“For now, we can only provide locals with information about the introduced species and the dangers that the species pose.
“They must be educated on the effect of these fishes on our native ones.
“This is a challenge, but public awareness is necessary to stop people from introducing alien species into our rivers. Consistent catching programme and monitoring are needed.
“The future of local species is affected, but the rate and how severe it will be is hard to tell unless a monitoring programme is implemented.
“But for now, we know that the red tail catfish is dominating the environment as more of the species are being landed by fishermen.
“Fewer local species caught also suggests that the threat is serious and real,” he said.
The Fisheries Department, he said, should eradicate alien predatory species and the quarantine administration should stop the influx of unwanted foreign species before they caused bigger problems in the rivers and to other local species.
“I wish aquarium owners and hobbyists were more responsible and not release alien predatory species when they no longer want to keep them.
“I also wish to see the authorities play an active role in eradicating these alien species.
“The government needs to take a more serious stand in caring for our environment, especially the aquatic ecosystem.”
Aqmal Naser, a PhD student at UMT and who has been involved in research for five years studying ichthyofauna on rice agroecosystem in Seberang Prai, Penang, said preliminary observation showed that the African catfish, which was harvested for local consumption, fed on local species.
“This observation was made in a padi field. This fish (African catfish) may bring disruption to the depauperated ecosystem,” said Aqmal, who is studying inland fishes in rivers and streams flowing into the reservoirs of Kenyir and Temenggor, where there has been a decrease in fish population.
“We are losing inland water bodies to land conversion, and our rivers and streams are being invaded by alien species. The future looks scary for local fishes as more alien species are being landed.”