Unicornfish are herbivores that live in tropical waters around coral reefs and are part of the surgeonfish family, Acanthuridae. Their name comes from the hornlike extension of the snout present in some species. They range from the Indian to Pacific Ocean. Two species are common in Hawai’i: the bluespine unicornfish or kala in Hawaiian (Naso unicornis) and sleek unicornfish or opelu kala in Hawaiian (Naso hexacanthus).
Kala is grey to bluish green. They are characterized by their long horn projecting from between the eyes extending out to the front of the mouth. Opelu kala is grey to greenish brown and does not have a horn. Like kala, they have two pairs of immovable bucklers on the caudal peduncle.
Kala travel in small schools and are seen in channels and seaward reefs with strong surges. They feed on coarse leafy brown algae. Opelu kala are often seen in large schools in open waters. They are opportunistic feeders feeding on red algae and zooplankton such as crab larvae and other small invertebrates.
Hook and Line Reef Fishing
This fishery uses a variety of artisanal methods to catch reef fish, including handlines, and pole and lines. Catch rates are low, usually only a few pounds per hour with little bycatch (discards). These small-scale fishing methods are similar to those traditionally used by native Hawaiians.