Riffle Galaxias

This species is distinguished from all other species in the Galaxias olidus complex by the following set of characters: a shallow body with a straight ventral profile; long and shallow caudal peduncle, its peduncle length is greater than the caudal fin length; caudal peduncle flanges are poorly developed; the distinctive snout extends anteriorly from the thick and fleshy upper jaw as a fleshy protrubence, bulbous in lateral profile; nostrils of moderate length, ofter not visible from ventral view; subterminal mouth and lower jaw 81.5 (72.9-99.4) % of length of upper jaw; most anterior tip of snout level with about lower 0.3 of eye diameter; head wide and shallow; short pre-pelvic fin length, pectoral fin to pelvic fin length and post-orbital head length dimensions; large, ventrally oriented pectoral and pelvic fins (12.1-16.7 and 9.2-13.0 % SL respectively); low mean vertebral count of 51, although range is broad (47-55); pyloric caecae 0-1, when present it is short (1.0 % SL) and wide; gill rakers of moderate length, thin and sharply pointed; anal fin origin usually under 0.4 distance posteriorly along dorsal fin base; distinctive cryptic colouration and no black bars along lateral line (Ref. 98815).

Dorsal soft rays (total): 8 - 11; Analsoft rays: 8 - 12; Vertebrae: 47 - 54

Recorded from cold to relatively cool, clear water in flowing creeks to large rivers (1.0-20.0 m average width), usually in shallow (0.1-0.4 m average depth), fast-flowing and high energy riffles and runs 10c), though juveniles have been recorded moving upstream through slow water along the shallow edges of pools. Substrate in riffles and runs consists predominantly of a complex of abundant cobbles and pebbles, with smaller amounts of bedrock, boulder, gravel and coarse sand. Fish are typically found within the diverse substrate, either amongst or under rocks on the stream bed, or deeper in the interstitial spaces of the substratum. Usually not associated with aquatic vegetation, but have been found amongst small and large timber debris.

A freshwater fish not able to undertake diadromous migrations. It was collected at a density ranging from < 0.01-0.80 fish/m2, but as individuals are usually hidden amongst or within the substrate in fast-flowing areas which are difficult to sample, these values are considered a gross underestimate of its relative abundance. Also recorded from cold to relatively cool, clear water in flowing creeks to large rivers (1.0-20.0 m average width), usually in shallow (0.1-0.4 m average depth), fast-flowing and high energy riffles and runs, although juveniles have been recorded moving upstream through slow water along the shallow edges of pools. The substrate in riffles and runs are mainly a complex of abundant cobbles and pebbles, with smaller amounts of bedrock, boulder, gravel and coarse sand. Fish are typically found within the diverse substrate, either amongst or under rocks on the stream bed, or deeper in the interstitial spaces of the substratum. It is usually not associated with aquatic vegetation, but have been found amongst small and large timber debris. Adults often are solitary; juveniles and younger adults observed in loose shoals of 50+ individuals, moving upstream during the day in shallow, slow-flowing water along the edge of pools, between riffle habitats: fish 3.8-6.6 cm LCF were recorded moving upstream in the Acheron River and individuals < 5.0 cm LCF observed along the edge in the Steavenson River (Goulburn system) in late May 2001; and, individuals 4.9-6.7 cm LCF were collected moving upstream along the edge of a long pool in the Mitta Mitta River (upper Murray system) in late June 2002. This suggests active upstream dispersal by younger age-classes of fish. Individuals from the Steavenson River, downstream from Marysville, were found with cysts, possibly trematode metacercariae, embedded in the skin of the trunk and fins.This species is often collected with the native species Gadopsis bispinosus (Two-spined Blackfish), Galaxias olidus s.s., Euastacus armatus (Murray Spiny Crayfish), Euastacus crassus (Alpine Spiny Crayfish), a shrimp (Atyidae) and including the alien species Brown Trout and Rainbow Trout (Oncorhynchus mykiss), and less often with the native Galaxias oliros (Obscure Galaxias) and Broadfinned Galaxias (Ref. 98815).