The secrets of the ghost catfish, the small transparent fish that shines like a rainbow

You can see through this little thailand aquarium fish: Her skin is almost completely transparent. But when the light just hits him, his body glistens with his bright colors of the rainbow.

Now scientists have discovered how this fish, called ghost catfishcreate its iridescent glow.

That glow comes from within, according to a study published Monday in the journal Proceedings of the National Academy of Sciences. As the light passes through the skin of the fish, it hits tiny structures in the muscle that transform the light into a colorful spectrum.

The ghost catfish, sometimes known as the glass catfish, is a small species native to the rivers of Thailand, averaging only a few inches (centimeters) in length. It is sold worldwide as an aquarium fish.

Other creatures are too iridescent, creating the glowing rainbow effect where the colors change as you move. They usually have shiny outer surfaces that reflect light, such as the feathers of a hummingbird or the wings of a butterflyexplain Ron Rutowski, biologist at Arizona State University, who was not involved in the research.

But the ghost catfish he has no scalessays the main author Qibin Zhaoa physicist from Shanghai Jiao Tong University in China, who became fascinated with fish after seeing it in an aquarium store.

Instead, he has tight structures in his muscles that can bend light into rainbow hues, which researchers discovered after shining different lights and lasers on his body in the lab. As the ghost catfish swims, these muscles relax and tense, emitting a brilliant array of colors.

And a highly transparent skin, which lets in around 90% of outside light, is key: “We couldn’t see colors if the fish’s skin wasn’t so transparent,” Zhao said in an email.

Some species use their iridescence to attract friends or emit warning signals, But it’s unclear if the colors of the ghost catfish serve any purpose, Rutowski said.

(With AP information)

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