Malaysia’s freshwater is rich with life, but beneath the surface a silent invasion is taking place. Non-native fishes that are originally brought in through aquaculture, an aquarium trade, or accidental releases are now spreading rapidly and reshaping the our country aquatic ecosystems.

One of the most infamous culprits is the suckermouth catfish (Hypostomus Plecostomus, Pterygoplichthys spp) or better known as the Ikan Bandaraya. It was originally from South America, this armored catfish now lurks in many rivers in Malaysia. These fish burrow into the sand at riverbanks to lay their eggs and shelter their young, weaken the riverbanks and cause erosion. They breed rapidly and dominate rivers and lakes, outcompeting native fish for space and food. It is estimated that these catfish population in Malaysia m have reached 100,000 across the Peninsular.

Another troublemaker is the African catfish or locally known as Keli Afrika (Clarias gariepinus) that has been introduced to Malaysia for fish farming. It has become one of the most disruptive invaders in the country’s freshwater ecosystems. Once it escaped into rivers and wetlands in our local waters, the local species like the native walking catfish (Clarias batrachus) began to disappear because this species grows faster and more rapidly than Malaysia’s native catfish. The African catfish in Malaysia is a clear example of how a species introduced with good intentions can become an ecological threat. Its predation, competition, and ecosystem disruption highlight the need for stronger policies and responsible aquaculture practices. Without careful management, the African catfish will continue to alter Malaysia’s freshwater ecosystems, diminishing biodiversity and affecting the communities that depend on these waters for their livelihoods.

Tilapia (Oreochromis spp) tells a similar story, popular fish species on the dinner table.  This species originally comes from Africa and the Middle East, especially the Nile River Basin, lakes in East Africa. From these regions, tilapia was spread worldwide for aquaculture because it grows fast, tolerates poor water quality and is easy to breed. Today, has now become one of the most dominant invasive species in natural waters of Malaysia. The tilapia populations have exploded and leaving little room for iconic native fish like the Malaysian mahseer (Kelah), snakehead (Haruan), Jullien’s golden carp (Temoleh), Arowana and many more. This situation pushing these treasured species to the brink of extinction and forcing them into a desperate struggle for space, food and survival in their own waters.

The story of invasive fish in Malaysia is ultimately a warning. Once these outsiders take hold, they are here to stay. But with vigilance and cooperation, it is still possible to keep Malaysia’s rivers and lakes alive with the diversity that makes them unique.

How can we do to help?

As ordinary citizens, we can help reduce the impact of invasive fish in Malaysia by avoiding the release of aquarium fish into rivers and lakes, joining community fishing events that target these invaders fish, and spreading awareness about their dangers. Small actions such as reporting unusual fish sightings or supporting conservation projects can collectively make a big difference. Protecting Malaysia’s freshwater ecosystems requires everyone’s participation, and the actions at the community level can make a meaningful difference.

Don’t release, protect our rivers, protect our future.

References:
Saba, A. O., Ismail, A., Zulkifli, S. Z., Ghani, I. F. A., Halim, M. R. A., Ibrahim, M. A., Mukhtar, A., Aziz, A. A., Wahid, N. A. A., & Amal, M. N. A. (2021). Invasion Risk and Potential Impact of Alien Freshwater Fishes on Native Counterparts in Klang Valley, Malaysia. Animals, 11(11), 3152. https://doi.org/10.3390/ani11113152

Saba, A. O., Rasli, N. F., Ismail, A., Zulkifli, S. Z., Ghani, I. F. A., Muhammad-Rasul, A. H., & Azmai Amal, M. N. (2020). A report on introduced Amazon sailfin catfish, Pterygoplichthys pardalis in Gombak Basin, Selangor, with notes on two body patterns of the species. Pertanika Journal of Tropical Agricultural Science, 43(4), 693–703. https://doi.org/10.47836/pjtas.43.4.19

Low, B. W., Liew, J. H., Tan, H. H., Ahmad, A. B., Zeng, Y., & Yeo, D. C. J. (2022).
The invasion and impacts of the African sharptooth catfish (Clariidae: Clarias gariepinus) in the Malay Peninsula. Freshwater Biology, 67(11). https://doi.org/10.1111/fwb.13984

Yunus, A. (2024, October 24). Attack of the Monster fish. The Star, https://www.thestar.com.my/news/nation/2024/10/26/attack-of-the-monster-fish

Author: Dr. Nadiatul Hafiza Binti Hassan

            Unit Biologi, Pusat Asasi Sains UPM

Date of Input: 11/09/2025 | Updated: 12/09/2025 | emma