surgeonfish

surgeonfish

 or tang

Surgeonfish (Acanthurus leucosternon)

(credit: Jane Burton—Bruce Coleman Ltd.)

Any of about 75 species (family Acanthuridae) of thin, deep-bodied, tropical marine fishes that are small-scaled, with a single dorsal fin and one or more distinctive, sharp spines on either side of the tail base. The spines resemble a surgeon's scalpel and may be either fixed or hinged at the rear so that they can be opened outward and directed forward. Surgeonfishes are mostly algae eaters and usually do not exceed 20 in. (50 cm) long. The yellow surgeon, or yellow tang (Zebrasoma flavescens), is an Indo-Pacific species, and the blue tang (Acanthurus coeruleus) is found in the Atlantic and Caribbean.