Malaysia: Introduced fish disrupts water, habitat quality of river

The fish had the potential to weaken the river- bank structure caused by their burrowing habit during spawning season.
Esther Landau New Straits Times 7 Feb 19;

KUALA LUMPUR: The presence of Amazon Sailfin Catfish or ‘Ikan Bandaraya’ could threaten the native fish species and affect water and habitat quality of the Malaysian rivers and lakes, said Universiti Kebangsaan Malaysia (UKM) School of Environmental and Natural Resources Sciences senior lecturer Dr Abdullah Samat.

Besides that, the fish had the potential to weaken the river- bank structure caused by their burrowing habit during spawning season, he added.

“This kind of fish does disrupt our aquatic ecosystem.”

The fish, from the South American continent, is imported as a ‘janitor’ fish for the aquariums and once they have outlived their purpose or gets too big, it’s thrown away.

“Their presence poses a danger to the ecosystem in two ways — threatening native species, and reducing water or habitat quality.

“The condition will depend on several factors such as the population size of the fish itself.

“The fish rigorously disrupts the river bottom and causes continuous high turbidity in the water with their burrowing habit.

“Hence, there is no benefit that we can get from the fish in our waters,” he told the New Straits Times.

He also said the alien fish could survive and reproduce in a wide range of environmental conditions, from excellent to a very poor habitat quality.

He added they would reproduce throughout the year with the highest peak during the monsoon seasons, thus explaining the large population of the fish in local rivers.

“They can live in many environmental conditions, and have plenty of food (any type of organic matter) as this fish is a detritus feeder and almost no predators.

“They are abundant in many rivers, streams and lakes all over the country especially those flowing through cities and towns,” he added.

Asked on methods that can be used to eliminate or reduce the population of the alien fish, he said the use of piscicide, a chemical substance which is poisonous to fish, could be carried out.

The primary use of the substance (piscicide) was to eliminate a dominant species of fish in water and it is the first few steps in attempting to inhibit different fishes.

Piscicide can also be used to kill parasites and widespread species of fish.

'Ikan bandaraya' 'cleans out' local ecosystem
Esther Landau New Straits Times 7 Feb 19;

THE presence of ‘ikan bandaraya’ (Amazon sailfin catfish with a scientific name of Pterygoplichtys pardalis) in Malaysian rivers and lakes has proven to disrupt the local ecosystem.

The alien fish can burrow into the ground or riverbanks, causing erosion as well as turning the waters murky.

According to the Johor Fisheries Department, in the long haul, the erosion would get worse if the fish is dumped into the local rivers in large numbers.

The department said the increase in this alien fish population has and will negatively impact the habitat of local freshwater fish in the long run.

“No local fish can live in polluted waters or rivers,” it said.

“The alien fish undoubtedly also causes damage to gillnets and other fishing nets, hence affecting the fishermen’s catch or income.

“Fishermen from Sungai Skudai in Johor have complained to the department claiming that they have been losing catch of local fish. They claimed that they caught a lot of ikan bandaraya instead.

“The species is increasing due to the declining water quality or rise in organic materials (substances) in the Skudai river. There is also no competitor fish in the contaminated aquatic system,” said the department in a statement.

“According to a research conducted by the department in 2018, some 61 per cent of the Amazon sailfin catfish were caught in Sungai Skudai, Johor Baru.

“This species of fish has high tolerance towards unconducive environments and adapting to different water environments.”

However, the Amazon sailfin catfish does not eat fish of its own kind or other fish —it only feeds on organic stacks and polluted aquatic substances, including weeds in the rivers.

“The Amazon sailfin catfish will form its group or colony in waters that contain high organic substances because of pollution or developments in that particular area.

Dept to probe presence of alien species in Sg Skudai
Rizalman Hammim New Straits Times 7 Feb 19;

JOHOR BARU: The state Fisheries Department will take up to a month to conduct an investigation into the alleged presence of the Amazon sailfin catfish, commonly called ‘ikan bandaraya’, in Sungai Skudai here.

Its director Zamani Omar said a special team had been set up to conduct the investigation after a newspaper reported on the matter recently.

“We did not receive any report on the matter before it came out in the media. We need to investigate the matter to find out the real situation, including the effects on the ecosystem.

“The investigation is expected to take between two to four weeks. We don’t want to be too hasty because the news report said the issue had been ongoing for about 10 years.

“We want to know the real situation so that we can find out the cause of the problem and take the necessary action so that it does not recur,” said Zamani.

He added that the department had not received any report on the presence of the fish in other rivers.

Taman Tampoi Utama fishing jetty head Osman Kassim said rapid development in the surrounding areas recently had seen a rise in the alien species’ population.

“Now, every time after it rains, the fish would be frequently caught in the fishermen’s nets, causing a lot of time spent freeing and throwing them away.

“Previously, the fish could only be found in the upstream area of Sungai Skudai near the water gate, but now it can also be found downstream near Taman Tampoi Utama,” said Osman.

He also said fishermen could once net species like patin, talapia, baung and terubok, but now they could only find patin and keli in the river.

“We are not sure why the number of fishes have dwindled,” said Osman.

Fisherman Badrul Hisham Mohamed, 51, said the biggest ‘ikan bandaraya’ he had caught weighed about 500gm.

“Some of the fishermen could catch as much as 15kg of ‘ikan bandaraya’, and not other types of fish, especially after it rains.

“I hope the authorities will take the necessary action because this has affected our income,” said Badrul Hisham, who had been fishing in the river for about 40 years.

Don't dump 'municipal fish' into rivers and lakes
Esther Landau New Straits Times 7 Feb 19;

KUALA LUMPUR: The Fisheries Development Authority of Malaysia (LKIM) has called on the public not to throw or release the “ikan bandaraya”, popular as an aquarium cleaner, into rivers and lakes.

Its chairman, Muhammad Faiz Fadzil, said the massive population of the alien fish had affected the fishermen’s income where catch of local fish was scarce and fishing nets damaged.

He said the alien fish disrupted the rivers’ ecosystem as it fed on aquatic plants which were also a source of food for local freshwater fish.

“The ‘ikan bandaraya’ also feeds on fish larvae, thus affecting the sustainability of
local freshwater fish population.

“However, there is no data recorded on the population of the fish.

“This alien fish is kept in the aquariums of fish hobbyists for its natural ability to clean the tank by eating the algae, leftover food, sediment and dead fish.

“The dumping of this fish into the rivers has increased its population which will have short- and long-term effects such as damage to the fishery habitat, aquatic surroundings and biodiversity of the freshwater fish in Malaysia.

“It also indirectly affects the fishermen’s income,” Muhammad Faiz told the New Straits Times.

He added that a study on the matter would be done soon by the Fisheries Department and LKIM.

“LKIM also supports the recommendation by the Fisheries Department to amend the Fisheries Rules of 1951 to ensure sustainability of natural resources and fish is protected,” he said.