Blackstreak Surgeonfish

About

The Blackstreak Surgeonfish (Acanthurus nigricauda) is one of the more behaviorally interesting members of the surgeonfish family, largely because it doesn't behave like most of them. While its relatives tend to hover over hard coral reef structure, this species gravitates toward sandy lagoon floors and sheltered bays, often picking at algae around isolated coral heads rather than cruising the reef crest. In the wild it ranges widely across the Indo-Pacific, from East Africa and the Mascarene Islands all the way out to the Tuamoto Islands, reaching as far north as the Ryukyu Islands and south to the Great Barrier Reef. Notably absent from the Red Sea. It can be found singly or in loose small groups. The species carries a distinctive dark bar or streak near the shoulder, which gives it several of its common names. One thing worth flagging: some individuals have been documented as ciguatoxic, so this fish is not typically considered for the table. In the aquarium, it's a committed herbivore that needs consistent access to algae-based foods and vegetable matter. Given its potential adult size and active lifestyle, it's best suited to very large systems with experienced keepers who can meet its substantial space requirements.