[Story 2] Human hobbies fuelling spread of invasive fish, say experts

 

By SHYAFIQ DZULKIFLI

PETALING JAYA: At least 12 invasive alien species identified by Malaysia Biodiversity Information System (MyBIS) are believed to have entered the country through human activities, including the ornamental pet trade, aquarium hobby and recreational fishing, say experts.

However, experts said the actual number could be higher as invasive fish may also enter through activities such as aquaculture, fisheries and intentional releases.

Universiti Putra Malaysia (UPM) fish ecology and diseases expert Prof Dr Mohammad Noor Amal Azmai said invasive fish species were able to establish themselves because of their biological characteristics, which gave them an advantage over native species.

He said carnivorous species such as Asian redtail catfish, Amazon redtail catfish, peacock bass, and African catfish could threaten native fish populations by preying on them.

“These species can occupy the top of the food chain in areas where they are released, while having few natural predators in their new environment, allowing their populations to grow” he said.

Meanwhile, omnivorous and herbivorous species such as tilapia, pleco and sailfin catfish, posed a different threat by competing with native species for food, habitat and space.

“These species are usually highly tolerant of poor water quality, have high reproductive rates and can breed throughout the year,” he said.

Associate Professor Dr Mohd Hanafi Idris from the Faculty of Fisheries and Aquaculture Sciences of Universiti Malaysia Terengganu said some invasive fish species entered Malaysia through the aquarium trade, while others were introduced for recreational fishing.

One example is the painted pavon or speckled peacock bass (Cichla temensis), which was originally brought in as an ornamental aquarium fish before also being introduced by anglers for recreational fishing and stocked in fishing ponds.

He said the species became popular among anglers because of its aggressive strikes and fighting ability.

However, such characteristics could become problematic when the fish established itself in natural waterways.

Another example is the Asian redtail catfish (Hemibagrus wyckioides), which was introduced for fishing ponds and aquaculture activities.

Dr Hanafi said these fish could escape into nearby rivers when ponds and cages overflow during floods.

“Most invasive species are hardy and highly resilient,” he said, adding that some species could survive for extended periods outside controlled environments.

Both experts highlighted the ikan bandaraya (Hypostomus plecostomus) as one of the more concerning invasive fish species in Malaysia.

Prof Mohammad Noor Amal said the species was able to dominate freshwater habitats due to its tolerance, adaptability and ability to compete with native fish.

Dr Hanafi added that ikan bandaraya could also affect river ecosystems by burrowing into riverbanks, contributing to erosion.

He said greater awareness among pet owners, traders, anglers and the public was needed to prevent further spread of invasive species.

“Many people may not know whether a species can safely be released into Malaysian waters,” he said.