Ocean Watch

While snorkeling at Hanauma Bay recently, I saw a surgeonfish whose common name I could not recall. This name forgetfulness is not new to me, but it's still annoying. How can I not know the name of a fish I see on the reef practically every time I go snorkeling or diving?

It's easy. Of the world's 80 species of surgeonfish, Hawaii hosts 25, some similar in appearance and all having several names.

But help is at hand. Honolulu's Mutual Publishing and Bishop Museum Press recently published a book called "Surgeonfishes of Hawaii and the World."

After being unable to identify that fish, I vowed to go home, pull my copy of this book from my shelf and once and for all learn the names and features of Hawaii's surgeonfish.

But when I started reading this book, written by Hawaii's fish expert Jack Randall, I learned much more about surgeonfish than their colors and names.

Surgeonfish are tropical species bearing two sharp spines at the base of the tail, one on each side. These spines lie flat in a groove, but when the fish needs to defend itself, it flips its tail and the spines pop out like tiny jackknives. Someone thought these spines were as sharp as surgeons' scalpels, and that's how the family got its name.

People sometimes ask me why some surgeonfish are called tangs and others are called surgeonfish. I never knew the answer to that, but I do now: There's no good reason.

"Tang" is the German word for seaweed, and this term was tagged on 13 of 80 common surgeonfish names. The name probably came from how most surgeonfish graze on algae, another name for seaweed. Other than that, "tang" has no special meaning.

Algae grow best in shallow, sunlit waters, and that's where you find most surgeonfish. These are among the most numerous fish on the reef, and on most days Hawaii's coral reefs teem with countless members of this colorful family.

Usually, surgeonfish swim alone or in small groups, but some, like our convict tangs (manini in Hawaiian), have learned to feed in schools. This is to their advantage because some damselfish, also algae eaters, fiercely guard their pastures and chase single surgeonfish away.

When manini descend by the dozens, however, a single damselfish is easily overwhelmed.

It's hard to watch a lone little damselfish frantically trying to protect its food supply, but that's life in the ocean. Survival of the fittest is rarely more visible than on a coral reef.

As I read about surgeonfish, I found the one whose name I couldn't remember. It was an eyestripe surgeonfish, or palani.

Or was it a yellowfin surgeonfish, also called pualu? Or maybe it was that other pualu, a ringtail surgeonfish.

OK, I admit it. I'll never learn all the surgeonfish names. But at least I can now look them up with ease, and I know, finally, after all these years, why some are called tangs.