A small, slender fish with a medium sized head and mouth, and a gape that extends to below the middle of the eye. Maximum size 55 mm. There are two dorsal fins, almost joined together, with the second dorsal fin long-based like the anal fin. The caudal fin is rounded, and the pelvic fins are joined to form a cup-shaped disc. There are no scales on the head or nape in front of the first dorsal fin.
The head and body is tan to pale brown or grey/white, with scattered small dark brown blotches. There is a thin vertical black bar from each eye to the end of the gape. Five or six small brown blotches are present along the sides, often connected with white dashes. There is sometimes a black to blue spot apparent at the base of the first dorsal fin.
This is really an estuarine species in areas of freshwater discharge but is also found and can complete its lifecycle in freshwater streams and lakes. It is usually recorded in still or slow-flowing habitats with mud or silty sand substrates. It is a benthic, burrowing species. As a primarily estuarine species, it is relatively tolerant of elevated salinity.
Approximately 85% of the diet in the Coorong is amphipods (commonly known as beach hoppers or land hoppers) followed by polychaete worms (~3%) and flatworms (platyhelminths) (2.5%) with small quantities of ostracods and bivalves.
The Lagoon goby is a common and widespread estuarine species in coastal streams of Vic, SA and Tas. In the Basin it is only present in the lower Murray River where it is known mainly from the lower swamps (Mannum to Wellington), Lower Lakes (Alexandrina and Albert) and Coorong, where it occurs in about 1/3rd of wetlands sampled. Its distribution extends to wetlands upstream of Mannum, but not as far as Overland Corner. The species can be locally abundant. 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. In the Coorong, numbers declined as the drought intensified and the normally brackish water became hypersaline. However, it was still the 2nd most abundant larval fish at the Murray Mouth in the latter stages of the Millennium Drought The abundance of the Lagoon goby increased again after the restoration of freshwater flows to the Coorong following the breaking of the drought.
None known, but the lack of freshwater inflows to the Coorong during the Millennium Drought and resultant hypersalinisation was associated with significant declines in this species. A study in Lake Alexandrina in SA found that 33 % of juvenile (95–128 mm TL) alien redfin perch prey on Lagoon goby in lake-edge habitats. No individuals were recorded from the Sustainable Rivers Audit (2004–2013) or the MDB Fish Survey (2014/15–2021/22).
Bice et al. 2012, 2016a, 2017, 2020a; Bucater et al. 2013; Giatas et al. 2022; Higham et al. 2005; Hoese 1991; Smith et al. 2009; Wedderburn & Barnes 2016; Wedderburn & Hammer 2003; Wedderburn et al. 2007, 2014; Zampatti et al. 2010, 2011.
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