Meet the strange-looking Commerson’s frogfish

  • Meet the Commerson’s Frogfish

Meet the Commerson’s frogfish, one of Hawaii’s most unusual sea creatures! This very-strange-looking fish uses it fins as hands and walks across the reef in slow motion. Most of the time it does not move at all except to open its mouth slowly to breath. It just sits there on the coral reef motionless, but divers rarely see the adults because they blend in to the background so well that they just look like a rock, coral head or red sponge. I often will point one out to a fellow diver and they still won’t see it, even when they are close enough to reach out and touch it! The adults come in green, tan, red, white and brown colors, and they grow to about 10 inches long. When they are juveniles they are bright yellow!

When they do decide to swim they use jet propulsion to go forward slowly thorough the water. They gulp down water with their mouth and then shoot the water out under pressure from two openings on their back fins, propelling themselves forward. It is the most bizarre type of swimming I have ever seen any species of fish do. This fish also has a very unusual way of catching food. On top of its head is a dorsal spine that looks like a slender fishing pole with a little fleshy worm dangling at the end.

It uses this modified fin to lure in fish that think they may have found a worm to eat. When the prey gets close, the frogfish opens it mouth wide so fast that it sucks in the unwary guest. The frogfish mouth can open much wider then its own body so it can gulp down a fish almost as big as itself! This all happens so fast that it looks like a fish just disappears into the reef in a split second, never to reappear.

See the frogfish in action in “The World’s Guide To Hawaiian Reef Fish” at, and follow daily underwater marine life posts on Instagram at terry.lilley.


Terry Lilley, a marine biologist, lives in Hanalei. His websites include and

  1. paulot September 8, 2019 8:09 am Reply

    Another interesting marine article from Terry Lilley. Thanks TGI.

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