The red handfish uses its fins to walk across coral reefs.
The red handfish uses its fins to walk across coral reefs. Antonia Cooper

The red handfish (Thymichthys politus) is a surpassingly rare reef fish that makes its way around the Tasman Sea not by swimming but by walking on its distinctively hand-like fins. It is considered among the rarest fish in the world, with only 20 to 40 individuals known in a single population. But last week a diver spotted one of the rare creatures off the southeast coast of Tasmania and alerted the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS). Scientists from IMAS and the citizen science organization Reef Life Survey then went out for a closer look.

Antonia Cooper, a researcher at IMAS, and her team spent hours in the water and were about to call off the mission when they finally spotted one. “My dive partner went to tell the other divers that we were going to start heading in and I was half-heartedly flicking algae around when, lo and behold, I found a red handfish,” she said in a statement.

After that first sighting the divers spent another 30 combined hours in the water, and eventually identified a total of eight red handfish swimming—or scurrying, rather—around an area of about 10,000 square feet. “It’s gotta be close to being the rarest fish in the world,” said Rick Stuart Smith, a scientist at IMAS and the cofounder of Reef Life Survey said in an official video.

What’s especially interesting about this new population is that it lives in a different habitat several miles away from the other known population. “This second population is a huge relief, it effectively doubles how many we think there on the planet,” Stuart Smith added. “It also gives hope that there may be other populations out there.”