The Short-tail galaxias Galaxias brevissimus is a newly described species in the Galaxias olidus complex and is one of several species listed as critically endangered. The species was impacted by the Black Summer fires of 2019-20, and prior to that the severe drought in NSW in 2017-2019. Almost nothing was known of its distribution, abundance and ecology apart from its type locality and some subsequent random spot records. The species is only known from two locations approximately 30-40 km east of Cooma: one is on a handful of private agricultural properties in the Upper Tuross River catchment around Countegany, and a second is in a single isolated stream in Wadbilliga National Park. Ecological knowledge is essential if the species is to be managed and recovered.
Under funding provided by the Commonwealth Bushfire Recovery Program, investigations into distribution and reproductive ecology were conducted in 2021 and 2022. Surveys of the species’ distribution in the Jibolaro/Guinea Creek sub-catchment have expanded its known range to approximately 18 km, with the upstream limits of the distribution now largely quantified. A new subpopulation was discovered in Lantooley Creek (Guinea Creek tributary) and the downstream population limit (the barrier that prevents upstream trout invasion) in the Jibolaro/Guinea creek system is now known. In Bumberry Creek in Wadbillaga National Park, the extremely rugged and isolated nature precluded survey work but studies on the reproductive ecology of the species were possible at a single site. Galaxias brevissimus is an isochronal spawner with ripe individuals recorded from July-September. Fecundity varied from 155 to 1035 depending on fish size, with mean mature or ripe eggs oocyte diameters of 0.79 to 1.60 mm (depending on individual). The spawning site remains to be described.