A small fish with a flattened head, bulbous cheeks and an oblique, moderate to large mouth. Maximum size ~110 mm; commonly 80 mm. The gape extends to below the middle of the eye (females), or to well beyond the eye (males). There are two dorsal fins, the caudal fin is rounded, and the pelvic fins are joined to form a large cup-shaped disc. There are no scales on the head or nape in front of the first dorsal fin. The head and body is pale grey to brown, fading to cream on the ventral surface. The head is mottled. A series of 3–5 dark brown saddle-shaped blotches are present on the back, with a row of 6–9 mid-lateral brown blotches on the sides.
An estuarine generalist, the Tamar goby is also found in adjacent freshwater streams and lakes. It is usually recorded in still or slow-flowing habitats with mud or silt substrates and abundant cover from rocks, logs or aquatic vegetation. Benthic and burrowing, it constructs its own burrow or uses a vacated one. It spawns in spring and the male performs a ‘hopping’ courtship display to entice the female to the burrow. Females mature at 45 mm length and males at ~65 mm.
Tamar goby is a common forage fish, and an important prey species for a range of fish and birds in the Coorong and Lower Lakes. Tamar goby were the 3rd most important identifiable fish species in the diet of Australian salmon and 4th most important for medium sized Mulloway (400–700 mm) in the Coorong. Tamar goby diet in the Coorong is dominated by microcrustaceans, particularly amphipods (commonly known as land hoppers or beach hoppers) with these animals occurring in 90% of fish. Other common prey items include ostracods (seed shrimps) (28%), copepods (32%) and mysids (shrimp-like crustaceans) (18%).
The Tamar goby is common and widespread in estuaries of Vic, NSW, eastern SA and northern Tas. In the Basin, it is known only from the Lower Lakes (Alexandrina and Albert) and Coorong. The species also occurs in a small proportion of wetlands adjacent to the lower lakes/Coorong. In the Coorong the species can be locally abundant but did not occur in the hyper-saline locations during the Millennium Drought that were furthest from the Murray Mouth. Towards the end of the Millennium Drought the species boomed in the Lower Lakes as freshwater flows declined and salinity increased.
Numbers then declined again following the breaking of the drought in 2010. As with other small-bodied estuarine species in the Coorong, numbers declined as the drought intensified and the normally brackish water became hypersaline. No individuals were recorded from the Sustainable Rivers Audit (2004–2013) or the MDB Fish Survey (2014/15–2021/22).
None known, but the lack of freshwater inflows to the Coorong during the Millennium Drought and resultant hypersalinisation, resulted in significant declines in this species. A recent study in Lake Alexandrina in SA found that juvenile (95–128 mm TL) alien redfin perch prey on Tamar goby in lake-edge habitats. A study in Lake Alexandrina in SA found that 13 % of juvenile (95–128 mm TL) alien redfin perch prey on Tamar goby in lake-edge habitats.
Allen et al. 2002; Cadwallader & Backhouse 1983; Cheshire et al. 2013; Giatas & Ye 2015; Higham et al. 2005; Hossain et al. 2016, 2017; Larson & Hoese 1996b; McNeil et al. 2013; Smith et al. 2009; Wedderburn & Hammer 2003; Wedderburn & Barnes 2016; Wedderburn et al. 2014; Zampatti et al. 2010, 2011.
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