Male upland bullies are larger and more stocky than females, with bolder markings. The face is profusely marked with orange spots, and there is a cream vertical band at the base of the pectoral fins.
Like other Gobiomorphus species, the first dorsal fin of males features a coloured stripe. The colour of the stripe in upland bullies appears to be locally variable. Many populations have bright orange dorsal stripes, however some have bright green, pink, yellow, cream or uncoloured stripes.
Upland bullies are neither diadromous nor migratory – they remain in freshwater for their whole lives.
Over spring and summer, the male establishes and defends a ‘nest’ – usually a hollow beneath a rock. Males prefer larger nests, however when in the presence of a predator, more enclosed nest sites are favoured. While defending the nest, the male turns very dark, from brown to completely black.
When a female is ready to lay eggs, she enters the nest and turns upside-down to lay several hundred to a thousand oval eggs in a close-packed, single layer attached to the nest’s ‘ceiling’. The male then fertilises the eggs. The female leaves the eggs in the care of the male, which guards them until they hatch two to four weeks later.:74 Females may lay eggs up to eight times over the spawning season, and one male may defend the eggs of more than one female.