This beautiful, six-inch–long butterfly fish is just one of about 25 species of butterflyfish that live in Hawai‘i, but it also lives all through out the tropical Pacific Ocean and the Indian Ocean. When you think about how Hawai‘i is over 2,000 miles away from other tropical coral reefs it is amazing that any of these delicate fish ever made it that far across the sea. Most likely at some point in time their eggs drifted in a current that made it all the way to Hawai‘i.
Haulau means “looks like the leaf of the hau bush.” When you are out snorkeling or diving and see a hau bush leaf or flower float by you will know why this fish got its name. The hau bush is the thick green bush with yellow flowers that grows along the banks of Hawaiian streams and rivers.
Many of the Hawaiian butterflyfish live in large schools but the teardrop butterflyfish usually is just seen in pairs. You can find them in five feet deep of water all the way down to 80 feet deep. They are very specialized feeders eating the polyps of the rice coral. When we do our scientific coral reef survey work we count how many haulau we see on the reef to give us and idea as to how health they rice coral population is. You will see this fish picking at the healthy rice coral but it is actually only feeding on the sick coral polyps which makes room for new healthy coral to grow. So these fish are very important to the health of the coral reef.
Most butterflyfish are very necessary for a healthy Hawaiian coral reef and many have the Hawaiian name kikakapu which means “highly forbidden”. In old time the Hawaiians knew it was important to not take the butterflyfish off of the reef as it was necessary to keep the corals healthy which are the home of the baby fish that grow up to be good fish to feed the community.
You can see haulau in action in my movie The Worlds Guide to Hawaiian Reef Fish up on my underwater educational web page at www.underwater2web.com.
Aloha from under the surf.
Terry Lilley, a marine biologist, lives in Hanalei. His websites include underwater-2web.com and www.gofundme.com/5urrm4zw