Watch: Cave-Climbing Fish Found—Is It Evolution in Action?

Filmed shimmying up a cave wall in Ecuador, the catfish is likely a known species with a never before seen behavior, a new study says

Foto: National Geographic

Deep beneath the Amazon rain forest lives a cave-climbing fish—and scientists have captured it on film for the first time.

A team exploring limestone caves near Tena, Ecuador (map), found the gravity-defying fish scaling near-vertical rock walls some 10 feet (3 meters) above an underground stream.
They later identified the species as Chaetostoma microps, a member of the suckermouth armoured catfish family (Loricariidae), according a study published April 16 in the journal Subterranean Biology.

Although that identification isn't 100 percent certain—for one, the expedition team wasn't authorized collect animal specimens in the caves—C. microps has previously been recorded only in aboveground rivers, where it clings to rocks. (Also see "How Fish Evolved to Climb Waterfalls With Their Mouths.")

While climbing fish are nothing new, the only other cave climber known to study leader Geoff Hoese is a loach from Thailand dubbed the waterfall-climbing cave fish (Cryptotora thamicola).

This fish is able to climb rapids and waterfalls, but Hoese questioned whether it can negotiate "cave walls outside of the main stream flow, such as we observed here."

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