Extraspecific imposition of social grouping among surgeonfishes (Pisces: Acanthuridae)

The Manini is a widely distributed surgeonfish that is often abundant on reefs. It has two modes of existence, scattered individuals or dense column‐forming schools, which may be seen on the same day at different places on the reef. In Hawaii schooling is a tactic used for getting to the bottom to feed when the bottom is held by territory‐holding food competitors. Mixed‐species “flocks” are an extension of this tactic. In atoll situations habitat partitioning exists, with the Maninis feeding in the intertidal area away from competitors; there, schooling is anti‐predator behaviour.