Most fish are content to, you know, swim. But then there's the shellear fish, a tiny, tenacious creature in the Democratic Republic of Congo that apparently missed the memo. Biologists have now officially confirmed that this little overachiever spends nearly 10 hours scaling waterfall cliffs, just to get where it's going.
Turns out, this isn't some new, extreme sport for the Parakneria thysi. It's a grueling commute to find better digs. The downside? All that effort makes them a glaringly easy target for illegal fishing. Because apparently, even fish can't have nice things without someone trying to exploit it.
For over 50 years, locals in the DRC have swapped tales of these climbing shellears, each one only about 1.4 to 1.9 inches long. Think of it: a fish smaller than your pinky finger, tackling a vertical rock face. But scientific proof? That took a team led by biologist Pacifique Kiwele Mutambala, who spent from 2018 to 2020 documenting their aquatic mountaineering at Luvilombo Falls.
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These tiny daredevils typically embark on their epic climbs between April and May, as the rainy season winds down. They use little hook-like growths on their fins to grip, wiggling their bodies side-to-side for extra propulsion, all while the waterfall actively tries to send them back to square one.
It's not a quick trip. The research team clocked a shellear fish taking approximately 9 hours and 45 minutes to conquer the nearly 50-foot Luvilombo Falls. That includes about 15 minutes of actual climbing, 30 minutes of mini-breaks, and nine full hour-long rests. Imagine that efficiency report. And success isn't guaranteed; one wrong move, one strong jet of water, and it's back to the bottom to start the whole ordeal again.
Why bother? Biologists have a few theories. Maybe they're just trying to get back upstream after heavy rains wash them down. Or perhaps they're seeking out prime real estate with better food options and fewer predators, like the delightfully named silver butter catfish. Whatever the reason, it's clear these fish are putting in the work.
Unfortunately, this incredible feat of endurance also paints a giant target on their backs. That long, slow line of climbing fish is practically an open invitation for illegal fishing. The area also faces threats from plans to divert the river upstream for crop irrigation. If conservation efforts in Upemba National Park falter, these tiny, determined climbers could disappear entirely. Here's hoping their incredible story highlights just how crucial these ecosystems are – and why we should probably let a fish climb a waterfall in peace.
