Bluegill bully

The bluegill bully (Gobiomorphus hubbsi) is a fish in the family Eleotridae that is endemic to New Zealand. It lives in shallow, fast-flowing riffles and torrents, where it forages and shelters amongst the gravels. It has a similar distribution to the other endemic riffle specialist, the torrentfish. It can be found up to 100 kilometres (62 mi) inland, and from sea level up to an elevation of 480 metres (1,570 ft). 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. The species is crepuscular with the most active times for feeding at dawn and dusk. They feed predominantly on Deleatidium mayfly nymphs.