A medium sized, laterally compressed, deep-bodied fish with a small head and mouth, large eyes and blunt snout. Maximum size ~470 mm; commonly 120–200 mm. The tail is large and deeply forked.
The single dorsal fin is short-based and in larger individuals it has a greatly elongated last ray that sometimes extends to the base of the tail. The pectoral fins are small; the pelvic fins are approximately midway along the belly, below the dorsal fin; and the anal fin is long-based. Scales form a serrated ridge on the belly.
The back is greenish, the sides bright-silvery iridescent and the belly silvery white; there is no lateral line.
Bony herring are a hardy fish, tolerating high temperatures (up to 38°C), high turbidity, high salinity (up to at least 39 ppt) and low dissolved oxygen. However, they are not tolerant of low water temperatures (die-offs of this species are commonly reported in winter) and, hence, are considered susceptible to the effects of cold-water pollution. Low water temperature is thought to depress the immune response, allowing increased infection by protozoan parasites and fungi.
In the lower Murray, males mature at 1–2 years and females at 2 years. Fecundity is high, with 33,000–880,000 eggs produced, depending on fish size. The small eggs (0.83 mm diameter) are released in October–February. In the lower Murray River significantly more (and smaller) individuals were caught below weirs during the day than at night by boat electrofishing. Daytime upstream movements have been recorded for juveniles and adults in the Murray and Murrumbidgee Rivers, and individuals as small as 22 mm have been recorded migrating. These movements are possibly related to the colonisation of new habitats by juveniles, as well as reproductive movements by adults. Low light levels (e.g. in road culverts) could be a barrier to movement by this species.
A study in the ephemeral, semi-arid Moonie River in Qld found that the species was much more sedentary than Golden perch or Freshwater catfish, with few fish moving from their waterholes during river rises. Bony herring were the most abundant large-bodied fish species moving between the main channel and perennial wetlands in spring in the lower Murray River, and were second only to Australian smelt of all fish species recorded moving.
The species feeds predominantly during daylight hours. It is a detritivore, consuming large quantities of detritus, microalgae and microcrustaceans, with microcrustaceans important for all size classes, but particularly for juvenile fish (<100 mm length). Detritus from decomposing terrestrial vegetation is the dominant food item of non-juveniles and the amount of algae consumed varies widely between studies.
Benthic algae can form ~20% of the diet of adults at some sites, with algae more important for large fish. In the Moonie River in southwest QLD benthic algae was the dominant dietary item during flow periods (‘boom’) with the diet switching to filamentous algae and detritus during non-flow (‘bust’) periods. Microcrustaceans were more significant in the diet of juveniles than adults from the Murray River.
Bony herring are consumed by other fish such as Murray cod and Golden perch, and also form a significant part of the diet of waterbirds such as cormorants and Pelicans. Bony herring was the most important identifiable fish species in the diet of small Mulloway (<400 mm) and 3rd most important in 400-700 mm Mulloway in the Coorong.
There is a historic report that the Nyeri Nyeri aboriginal nation considered Bony Herring to be an aphrodisiac and so taboo to young women.
Widespread and abundant, Bony herring vie with Spangled perch for the distinction of being the most widespread of Australia’s native freshwater fish species. Most common in lowland river systems generally, in the Basin it is known from the majority of lowland rivers, where it is usually the most abundant large-bodied native species. It was the most abundant native fish species in the Sustainable Rivers Audit (46,982 individuals: 21.5% of total catch) with 46% caught in lowland zones and 72% coming from just 4 of 23 valleys (Darling, Lower Murray, Warrego, Condamine).
In the MDB Fish Survey it was the second most abundant fish (behind carp gudgeons) with 40,115 caught between 2014/15 and 2021/22. It is commercially fished in Lake Alexandrina, SA. In the Basin, the species is largely absent from upland habitats, probably due to low water temperatures. A close relative of Bony herring, the Perth herring, was canned and sent to Australian troops during the Second World War, but neither species is highly regarded as an eating fish, and the troops did not approve!
Some aspects of river regulation (barriers to fish passage, coldwater pollution) have reduced the abundance of Bony herring in some areas and it is now in low abundance in the Murrumbidgee and upper Murray rivers below Burrinjuck and Hume Dams. The barrier formed by Burrinjuck means that the species is no longer sporadically recorded upstream of this dam.
However, in contrast, Bony herring in the Lower Murray are thought to have increased in abundance as a consequence of river regulation, as they are tolerant of many aspects of altered flow regimes and have an opportunistic reproductive strategy. Abundance of this species in the Lower Murray declined noticeably during 2012 following the breaking of the Millennium Drought.
Allen et al. 2002; Balcombe et al. 2005; Baumgartner 2003; Baumgartner et al. 2008, 2010; Bice et al. 2014; Bishop et al. 2001; Briggs & McDowall 1996; Conallin et al. 2011; Giatas & Ye 2015; Humphries 2009; Jones et al. 2017; Marshall et al. 2016; Medeiros 2004; Puckridge & Walker 1990; Pusey et al. 2004, 2021; Smith et al. 2009; Sternberg et al. 2008.
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