Bluegill bully (Gobiomorphus hubbsi)

The bright blue gill membrane just behind the head readily distinguishes the aptly named bluegill bully from other members of the Eleotridiae family. This membrane is present in both male and female bluegills. However, the small dark spots that cover their cheeks are another useful characteristic. When viewed from the top bluegill bullies are arrow shaped, with their narrow elongate body trailing behind the larger head.

Bluegill bullies inhabit similar habitat as torrentfish - swift broken water in open rivers and streams. They also have a similar distribution pattern to torrentfish, being absent from Fiordland, Stewart and Chatham Island, and rare in Otago and Southland. Overall, they are not as common as torrentfish, particularly in Taranaki and Coromandel.

Bluegill bullies are the smallest members of the Eleotridiae family in New Zealand. The largest specimen recorded is a 100 mm bully, but most adults are between 60–70 mm in length. In common with all the bully species, bluegill bullies are benthic, i.e. they live right down on the substrate, and appear awkward when trying to swim to the surface. Rapid flapping motions seem to get them there, but they soon sink back down, often tail first! Bluegill bullies are strictly carnivorous, and their food mainly consists of mayfly larvae.