Previously considered to be Mountain galaxias, recently revised and formally reinstated as a separate species. Much of the following information is from Raadik (2014).
A small and strikingly coloured fish. Maximum size 165 mm; commonly 80–105 mm. Scales are absent, the tail is weakly forked or occassionally truncate, and the anal fin originates at around 0.7 of the distance posteriorly along the dorsal fin base. The head is large and long, distinctly wider than deep, the gape is wide.
The body is an unmottled yellow-orange, red-orange or orange colour paling to light yellow-orange to cream on the belly. There are 1–10 (usually 7 or less) complete or partial vertical ovoid black bars on the sides (not on the dorsal surface) between the rear of the gill cover and pelvic fin bases (whereas in Mountain galaxias the stripes/bars usually extend well behind the pelvic fin base).
Barred galaxias occurs in small to medium-sized, shallow, cool, clear, upland streams with moderate to fast flows and stony or sandy substrates. Much is still unknown of its ecology owing to its highly threatened status and small population size. The preferred habitat is thought to be slow-flowing, deep pools adjacent to riffles and cascades.
Spawning is likely triggered by an increase in day-length and possibly water temperature in mid-August–late September. Average fecundity is about 500 eggs, but egg masses are smaller than this: usually < 80 but up to 218 eggs, suggesting that females may spawn at multiple sites. Water-hardened and fertilised eggs are large (3-4 mm diameter), spherical and demersal. The eggs are laid in a multilayered mass on the stream bed on the downstream side of cobbles or boulders when water temperatures are around 8–10° C.
The spawning sites are in moderate to fast flowing habitats which are shallow (~175 mm depth) and located immediately upstream of pools. Time to hatching in the wild is unknown, but larvae hatched after 30–48 days in aquaria at ~10°C and were 8.5–10 mm long upon hatching.
Movement requirements are unknown, but the species is thought to be non-migratory and relatively sedentary, judging by recolonisation rates of streams where trout have been removed. Potentially good at climbing over wet rocks as paired fins have special structures to aid climbing, similar to those in the Climbing galaxias.
The diet consists of drifting and benthic aquatic invertebrates with fish foraging off the bottom and mid water in pools and at the bottom of riffle/glide sections. The species is relatively long-lived for a small fish-individuals up to 15 years old have been recorded.
Barred galaxias has suffered a catastrophic decline of >95% of its likely historical distribution and abundance, it is now only found in the headwaters (above 400 m altitude) of the Goulburn River catchment in the central highlands of Vic, in the southern Murray–Darling Basin. Historically it occurred in larger, lower elevation streams (around 300m altitude).
There are only 12 geographically isolated known populations of this species still extant, and at least five previous populations are now extinct. The total length of streams for all known populations is <20 km. Essentially the only species in the G. olidus complex found within its range, although at one site (Raspberry Creek) it co-occurs with G. olidus. 79 individuals were recorded from the Sustainable Rivers Audit (2004–2013), all in the Goulburn catchment uplands zone. None have been recorded in the MDB Fish Survey (2014/15–2021/22).
Interaction with Rainbow and Brown trout (mainly predation) is the major threat to the Barred galaxias. Following the invasion or introduction of trout, the species is rapidly eliminated (1-2 years) from streams where it was formerly abundant. It has been recorded in gut samples of trout captured in Barred galaxias habitat, and juvenile galaxias are the most severely impacted by predation. Competition between larger Barred galaxias and trout may be a secondary threat.
The species was seriously impacted by the 2009 bushfires and subsequent rainfall which deposited ash and sediment into streams, approximately 50% of the species range was impacted by these fires, with most of the remaining range also burnt in 2006/07.
Sedimentation is considered a major threat, smothering spawning sites and other critical habitats. Bushfire debris and flooding may also change stream topography, drowning out small barriers which may have excluded trout. Drought may result in the loss of surface water, threatening small, isolated populations. As a result of the small, fragmented distribution of the species, local habitat modification and degradation could also threaten populations. Barred galaxias now exist only in trout-free streams with physical barriers to exclude upstream invasion by trout an essential part of their management.
Ayres et al. 2011; Lintermans & Raadik 2003; Lintermans et al. 2014; Raadik 2000, 2011, 2014, 2019a; Raadik et al. 1996, 2010; Shirley & Raadik 1997; Stoessel et al. 2015, 2020b.
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