The Unstoppable Invader: Understanding the ‘Walking’ Ability of the Armored Catfish
For years, anglers and environmentalists believed that removing the invasive suckermouth catfish—known locally in Indonesia as ikan sapu-sapu—from the water was a simple way to manage their population. Though, recent findings have revealed a startling biological adaptation: these fish can actually “walk” on land to find their way back to the river.
This behavior transforms a manageable pest into a resilient survivor, challenging current efforts to protect native aquatic ecosystems from the Loricariidae family.
The Science of ‘Reffling’: How a Fish Moves on Land
Research conducted by American scientists Noah R. Bressman, Callen H. Morrison, and Miriam A. Ashley-Ross, published in the Journal of Ichthyology & Herpetology (Volume 109, Issue 2, 2021), has decoded this surprising movement. They identified a technique called “reffling.”
Because their bodies are covered in longitudinal rows of armor-like scutes, these fish lack the flexibility of other species. To compensate, they use a bouncing motion, pushing their bodies forward by bouncing their tails and fins against the ground.
This adaptation was highlighted in reports from Florida, USA, where residents and city officials frequently spotted these fish on land, initially assuming they were discarded by fishermen or escaped from ponds.
Beyond the Water: A Global Ecological Threat
The Hypostomus plecostomus and its relatives, such as the Pterygoplichthys pardalis (Amazon Sailfin Catfish), are native to tropical northeastern South America, including Brazil, the Guianas, and Trinidad and Tobago. However, they have become invasive across the globe, from Europe to India and Southeast Asia.
Their impact on local environments is severe. As highly invasive species, they consume vast amounts of algae, which serves as a critical food source and shelter for other native aquatic animals.
Survival Against the Odds: Predators and Pollution
The armored catfish is not only difficult to remove from the water but also difficult to kill. In Florida, the Blue Heron—a natural predator—often attempts to eat these fish. However, the catfish’s hard skin makes them difficult to swallow, leading the birds to simply drop them on land. Thanks to “reffling,” these fish can then navigate their way back to the water.
species like Pterygoplichthys pardalis demonstrate an incredible resilience to environmental degradation. In Indonesia’s Ciliwung River, these fish have been found to be resistant to organic pollution and heavy metals, including:
- Cadmium (Cd)
- Mercury (Hg)
- Lead (Pb)
This ability to thrive in contaminated waters allows them to dominate urban river systems where other fish species might perish.
Future Trends: Climate Change and Habitat Expansion
The expansion of the armored catfish is closely linked to water temperature. While they generally avoid cold water, the trend of global warming is making more regions habitable for them. As river and lake temperatures rise, the geographic range of these invasive fish is expected to grow.
Environmentalists warn that the trade of these fish as aquarium “bottom cleaners” continues to fuel the problem. Releasing pet plecos into local waterways provides a direct pathway for these resilient survivors to establish new colonies.
Frequently Asked Questions
Q: Why is the suckermouth catfish called an “armored” catfish?
A: They belong to the Loricariidae family and are named for the longitudinal rows of armor-like scutes that cover the upper parts of their head and body.
Q: Can they really move on land?
A: Yes, through a process called “reffling,” where they bounce their tails to push their bodies forward.
Q: Are they safe for human consumption?
A: While they are occasionally consumed in their native range and in places like the Ciliwung River, they can accumulate hazardous heavy metals (Cd, Hg, and Pb) from polluted waters, which may pose risks to human health.
Want to help protect our waterways? Share this article to spread awareness about the dangers of releasing aquarium pets into the wild, or leave a comment below to tell us if you’ve spotted these “walking” fish in your local area!
For more information on invasive species and aquatic biology, visit the Wikipedia page on Hypostomus plecostomus.
