Common bullies are more found in many habitats, sometimes being especially abundant. They are found in almost all habitats; from streams to lakes, and from rivers to wetlands. They feed on small bottom-dwelling insects and crustacea; being flexible in their diet to what their particular habitat has to offer. Preferring slower waters, they may be migratory or exist in landlocked populations such as in some lakes. The male is often darker than the female, and also features an orange tip across its first dorsal fin. He vigorously defends the nest in which the female has laid her eggs and which he has consequently fertilised, by turning a dark black colour and attacking all comers regardless of sex or species. The common bully grows to around 110 mm long, and can live for over 3 years.

Conservation status: Common bullies are one of the few native fishes that have not shown a drastic reduction in numbers and distribution following the arrival of humans to New Zealand.

This species has only fairly recently been distinguished from the sometimes very similar and closely related common bully (G. cotidianus), and consequently little is known of its ecology. Crans bullies, however, are known to be non-migratory, typically being found in inland streams hiding under cobbles in gently flowing currents where they feed on small stream invertebrates. Males feature a bight orange stripe on the tip of their first dorsal fin, their whole body turning a dark black when defending their nests in spring. The shape of crans bullies varies between populations, but with heads being much blunter than for common bullies. They are often very approachable in the wild; sometimes perching in one hand on their pelvic fins at the front of their belly like a parrot.

Conservation status: Found only in the North Island, areas with good water quality may sometimes support very high numbers. Nationally this species has been affected by habitat destruction and migration barriers.

This stunning fish is often regarded as the most attractive of our native freshwater fishes, with the different sexes being demonstrated in this species with the male having bright red coloured dorsal fins and side patches. Highly territorial, they are usually found in small pools in fast flowing small to medium sized streams contained by a forested catchment where overhead vegetation and a coarse substrate is present. Prey consists largely of aquatic insect larvae found under the rocks and cobbles. As with many of New Zealand's other freshwater fish fauna, spawning occurs in freshwater with the young being swept downstream to live in the sea. A few months later they swim back to a freshwater adult life via a coastal stream or river mouth.

Conservation status: Frequently rare in deforested regions, areas with good forest cover may support high populations. More common in streams near the coast, nationally this species has been reduced in numbers through habitat destruction and migration barriers.

So named because of its bright blue gill-margins, the bluegill bully was first noticed as a separate bully species in our freshwater fish fauna as late as 1949. It shares its typical habitat of swiftly flowing waters of cobbly streams near the coast with the torrentfish, albeit at the edge of this other fishes' preferred turbulent white-water areas. These waterways are found right around the coastline of New Zealand, giving this fish a large distribution. However, because of the nature of this habitat, even people regularly using the streams and rivers that they inhabit, rarely see them. Their feeding habit is based on picking aquatic insects off of the undersides of the rocks found in its fast-water habitat, with its protruding lower jaw. Feeding is therefore quite selective, with most of the activity of this fish being at dusk and dawn when its insect prey is found to be most active.

Conservation status: With large numbers often found in braided rivers, bluegill bullies have not been as seriously affected by the removal of native forest cover as have other species. They are still fairly common.

The giant bully is the largest of the bullies, built solidly with a extended lower jaw and commonly found more than 150 mm long. Females are smaller than the males, and have a blunter head and more straight-edged fins. When small all giant bullies may be easily confused with common bullies (Gobiomorphus cotidianus). They are a coastal area fish, mainly found in estuaries and the lowest reaches of rivers and streams, just above low tide, right around New Zealand. Little is known of the biology of this species, as their estuarine environment is little studied due to the difficulty of access. However, it is expected that they feed on small animals found around during their main period of feeding activity at night. During the day they may be found underneath large rocks and in bankside crevices.

Conservation status: Although not commonly encountered, this is probably more due to the inaccessibility of lowland stream and river channels than to a low abundance of this widespread species.