Taxonomy & naming
Stiphodon rutilaureus is a true goby of the family Oxudercidae, placed in the Sicydiinae, the amphidromous stream gobies of Indo-Pacific islands. The Catalog of Fishes lists it as valid under the authority Watson, 1996. The type locality is given there as: Letak Creek, about 25 kilometers southeast of Wewak, New Guinea, Papua New Guinea, elevation 1,148 ft.
Morphology
Sicydiine gobies have the pelvic fins fused into a cup-shaped sucker disc, which lets them hold position on rock in fast current and climb wet rock faces on the way upstream. Males in this group are usually more colourful than females. FishBase gives a maximum of 2 in SL for this species; a detailed colour description has not been compiled here.
Habitat
FishBase says the species inhabits swift, clear streams over rocky bottoms, at depths down to about 16 ft, and lists it as freshwater, demersal and amphidromous. The type locality, Letak Creek, lies at 1,148 ft elevation. Measured water chemistry has not been published.
Feeding
Stiphodon species are specialised grazers that scrape algae and diatoms from rock surfaces, and this species is expected to feed the same way. Its diet has not been described specifically.
Mating
Mating has not been described for this species. In better-studied sicydiines, males hold small territories on stream rock and court females at a nest site.
Breeding
FishBase lists the species as amphidromous. In that life cycle eggs are laid in fresh water, the larvae drift to sea, and the post-larvae return to rivers months later. Details specific to this species have not been published. It cannot be assumed to breed in a closed freshwater aquarium, and trade fish are wild-collected.
In the aquarium
Species in the trade under this name are demanding. They need cool to moderate, very clean, strongly oxygenated water, brisk flow, rock surfaces with mature biofilm, and a tightly closed lid. Husbandry for Stiphodon rutilaureus itself has not been documented, so general sicydiine practice is the only guide. Identity of fish sold under this name should be treated with caution.
Conservation
The IUCN assessed Stiphodon rutilaureus as Least Concern in 2019, meaning it is not currently considered at risk. Like other amphidromous gobies, it still depends on unobstructed streams down to the sea, so dams and stream degradation are the main concerns for the group.