This newly named fish, called "psychedelica," hops and crawls more than it swims. It also has a flat face and eyes that face forward, a feature unusual for fish.

David Hall/seaphotos.com

In January 2008, divers swimming off an Indonesian island saw an unusual fish. To try to identify the strange-looking swimmer, they took pictures and sent them to fish expert Ted Pietsch of the University of Washington in Seattle. Pietsch has been identifying fish species for 40 years. He studied the pictures and came back to the divers with an unexpected answer: That fish didn’t have a name.

He quickly figured out that the fish was an frogfish — and he should know, since Pietsch has been studying frogfish for decades. Pietsch also figured out that no one had ever described that particular kind of fish in scientific terms before. One year later, he became the first to do so. The first scientist to describe a species gets to name it. Pietsch named the fish “psychedelica” (Latin name Histiophryne psychedelica).

Psychedelica, about four inches long, is unlike any fish in your local aquarium. What’s the strangest fact about this fish? After reading about it, you decide.

They hop: If you saw one underwater, you probably would think it wasn’t swimming. The fish moves along a coral reef by squirting out little jets of water, so it appears to be hopping, rather than swimming. Its hops are irregular and strange, as you can see in videos at http://uwfishcollection.org/psychedelica/. No frogfish had ever been observed hopping before.

They crawl: On either side of the fish’s body are fins that work more like legs. The fish seems to prefer strolling along a reef to swimming through the water: crawl-hop-crawl-hop.

They see the world differently: The face of psychedelica is flat, and its eyes face forward. While eyes that face forward are common on humans, most fish have an eye on either side of their head. As a result, the two eyes see different views. Not so with psychedelica — Pietsch says he’s never before seen this trait in an frogfish.

They don’t change: psychedelica’s swirls and stripes stay the same regardless of where it is. Most frogfish are able to change their colors, depending on the environment in which they’re swimming. But psychedelica’s stay the same in any situation.

Perhaps the most bizarre thing about psychedelica is that Ted Pietsch had seen it before 2008. When he first received the new pictures from Indonesia, he thought they looked familiar. He went through his fish collection and found two specimens of the same fish, though those were faded and damaged. They were sent to him by the Dallas Aquarium — 17 years ago.