Meet kikakapu, the lined butterfly-fish

  • Terry Lilley / Special to The Garden Island

    Kikakapu is the Hawaiian name for the lined butterfly-fish.

Many butterfly-fish live in schools and hang out together, but this rare Hawaiian butterfly-fish is a master at social distancing. You almost always see them in pairs, and they have a large territory of coral reef and actively chase others of their own species out of their territory.

They always have their black mask on, and even avoid other fish species. They are one of the most antisocial fish on the Hawaiian coral reef.

This unique butterfly-fish is the largest butterfly-fish in the world, growing over 12 inches long, and the largest ones in the entire Pacific live in Hawaiian waters. They live in shallow water all the way down to over 100 feet deep. I have done thousands of dives in Hawai‘i documenting our marine life, and I have never seen a baby lined butterfly-fish. They are quite secretive, hard to get close to, and little is known about them.

Like many other butterfly-fish the lined butterfly-fish eats coral polyps, so it needs a healthy coral reef to survive. It’s Hawaiian name, “kikakapu,” means “strongly forbidden,” and in old Hawai‘i you could get in severe trouble if you caught one.

The Hawaiians knew that these butterfly-fish eat the old, diseased and dying coral polyps, making room for new corals to grow, which keeps the coral reef healthy. They made it “kapu,” or illegal, to catch them for food, but sometimes they were collected by the ruling class to be used in ceremonies.

We have over a dozen different species of butterfly-fish here in Hawai‘i, and us scientists monitor their populations to determine how healthy the coral reef is in any given area. We call the butterfly-fish an “indicator species.” The more butterflyfish, the healthier the coral reef is.

In our upcoming Coral Reef Kids Camp we run in July at ‘Anini, we teach the students how to identify each butterfly-fish species, and show the kids firsthand how important they are to maintain a healthy marine ecosystem. Children can sign up for the Coral Reef Kids Camp by going onto the Facebook page for the nonprofit Reef Guardians Hawai‘i.

You can also see the lined butterflyfish and all of the kikakapu species in action on the underwater educational web page at in my movie “The World’s Guide to Hawaiian Reef Fish.”

Aloha from under the waves.


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


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