Invasive Pleco Fish Can Walk on Land to Return to Water

The Unstoppable March of the Pleco Fish: Why These Invasive Species Are Harder to Stop Than You Think

For many aquarium hobbyists and anglers, the pleco—known in Indonesia as the ikan sapu-sapu—is a familiar sight. Even as they are prized for their ability to clean algae, these fish from the Loricariidae family are becoming a global environmental nightmare. From the Amazon to Florida, Europe, and India, these invasive creatures are rewriting the rules of aquatic survival.

The real danger lies in a capability most people aren’t aware of: the ability to abandon the water and navigate the land to find a new home.

The Science of “Reffling”: How a Fish Walks on Land

Many people assume that throwing an invasive fish onto dry land is a guaranteed way to eliminate it. However, research published in the Journal of Ichthyology & Herpetology (Volume 109 Issue 2, 2021) by scientists Noah R. Bressman, Callen H. Morrison, and Miriam A. Ashley-Ross proves otherwise.

The study reveals that plecos use a technique called “reffling.” Because their thick skin reduces flexibility, they cannot swim or glide on land. Instead, they propel themselves forward by bouncing their tails and fins against the ground, effectively pushing their bodies toward the nearest water source.

This means that when anglers or homeowners discard these fish on a riverbank, they aren’t necessarily killing them—they may simply be giving the fish a chance to migrate to a new, untapped freshwater area.

The Florida Case Study: Predators as Unintentional Helpers

In Florida, the Blue Heron provides a fascinating example of how nature can inadvertently help an invasive species. These birds often attempt to prey on plecos, but the fish’s hard, armor-like skin makes them difficult to swallow.

When a Blue Heron gives up and drops a pleco on the ground, the fish doesn’t just die. Using the reffling method, the pleco can walk back into the water, surviving the encounter and continuing to disrupt the local ecosystem.

Future Trends: Climate Change and Habitat Expansion

The expansion of the pleco is not accidental; it is closely tied to shifting global temperatures. Historically, these fish have avoided cold water environments. However, as climate change causes river and lake temperatures to rise, more regions are becoming habitable for the Loricariidae family.

As water warms, we can expect to see these invasive species push further into previously “safe” cold-water zones. This expansion poses a severe threat to biodiversity, as plecos consume the algae that serve as critical food sources and shelters for other native aquatic animals.

Effective Control: Moving Beyond Simple Disposal

Since simply removing a pleco from the water is insufficient, environmental management strategies must evolve. To truly prevent the spread of this invasive species, more permanent methods of elimination are required.

• Avoid Shoreline Disposal: Stop throwing caught plecos on the grass or riverbanks.
• Permanent Elimination: Experts suggest that burying or completely destroying the fish is the only way to ensure they do not return to the water.
• Public Awareness: Educating the community on the “reffling” ability of the pleco can prevent accidental migrations.

For more information on managing invasive species, you can check out our guide on protecting local watersheds or visit reports on river quality indicators.

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