CRITTER: Meet maneoneo the Sailfin Tang - The Garden Island

Out on the Hawaiian coral reef, bigger is better! Most fish species try to look larger than they are when threatened by a predator, and the sail-fin tang is a master at changing its size when danger appears.

Maneoneo is a type of surgeon-fish because it has a very sharp spine at the base of its tail that is as sharp as a surgeon's scalpel. What is very unique about this fish is it has a dorsal and anal fin that are as large as the entire body of the fish. When they are alarmed they raise these two fins and they look like a boat with two sails. They can double their size in a split second, so if a large predator fish tries to eat them they will have a better chance to escape due to their increased size.

Maneoneo will turn sideways when attacked by a predator so it looks big but it has a very thin body. With the fins erect the sail-fin tang is over a foot long, but it can dart between coral heads because it is only an inch wide. When it is relaxed and is feeding on algae it lowers its sail fins and becomes half its size. This way it can blend into the larger schools of surgeon-fish species that also feed on algae growing on the reef.

In Hawai'i the sail-fin tang is quite rare, and you usually find them in pairs. They are also territorial, so they are spaced out evenly on the reef. In Palau and Tahiti, often these fish will form large schools, but they do not seem to have that behavior here in Hawai'i. As a diver it is hard to get close enough to this fish for it to become alarmed where it will put up its sail fins, so I actually had to corner one in a cave to finally get a good picture of it. The babies are bright yellow and have huge fins, but they are very hard to find. Out of over 1,000 scuba dives I have done in Hawai'i I have only seen about 10 babies, and they were all in shallow, calm water.

In old Hawai'i many of the fish names relate to how the fish behaves out on the reef or what the fish taste like when speared and eaten. The sail-fin tang's Hawaiian name maneoneo means "itchy or irritating" because when you eat it raw it can cause irritation in your throat!

You can see maneoneo in action in my movie "The World's Guide to Hawaiian Reef Fish" up on my underwater educational web page at www.underwater2web.com.

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Terry Lilley is a marine biologist living in Hanalei and co-founder of Reef Guardians Hawai'i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawai'i go to www.reefguardianshawaii.org.