The bluegill bully (Gobiomorphus hubbsi) is a sleeper goby endemic to New Zealand. It is a specialist of shallow, fast-flowing riffles and torrents, where it lives amongst the gravels. It a similar distribution to the other endemic riffle specialist, the torrentfish. The bluegill bully is the smallest of the Eleotrids, commonly reaching only 60–70 mm (2.4–2.8 in). It is named for the bright blue edge to the operculum or gill cover, which is present in both sexes. It eats aquatic invertebrates and has an upturned mouth, allowing them to pick invertebrates off the stones above them.