Full text can be accessed at http://hdl.handle.net/2066/34870Little is known about fish assemblages on seagrass beds located adjacent to different habitats. Visual census surveys were used to study the fish composition of two types of seagrass habitats in Zanzibar (Tanzania): seagrass beds adjacent to extensive mangrove areas in an embayment (bay seagrasses) and seagrass beds situated on the continental shelf adjacent to coral reefs (reef seagrasses). At species level, 39 fish species were common in the seagrass habitats, of which nine showed significantly higher densities in bay seagrasses, and four species were exclusively observed in bay seagrasses. Seine net data supported these data a the connectivity with mangroves.