Blackstreak surgeonfish, Acanthurus nigricauda, or epaulette surgeonfish, eye-line surgeonfish, shoulderbar surgeonfish, white-tail surgeonfish, is a tropical fish in the family Acanthuridae. It is native to the Indo-Pacific region. It occurs over sandy and rocky bottoms, in bays, lagoons and on reef slopes, at depths down to about 30 m.