The southern pygmy perch (Nannoperca australis), also known as the Tasmanian pygmy perch, is a species of freshwater ray-finned fish, a temperate perch from the familyPercichthyidae which is native to south-eastern Australia and Tasmania.
The southern pygmy perch has an oblong and moderately compressed body with a convex dorsal profile and a straight ventral profile. It has a large head the top of which bulges slightly and a blunt snout. It has a slightly oblique, terminal mouth which is protractile with the maxilla reaching to a level near the centre of the eye. There are thin bands of villiform teeth on the jaws and the roof of the mouth. There is a lateral line made up of an irregular series of pored scales. The dorsal fin has 7-9 spines in its front part, separated from the rear part by a deep notch, the rear part contains 7-10 soft rays. The anal fin is similar in shape to the soft part of the dorsal fin and has 3 spines and 7-8 soft rays. The large caudal fin is rounded.[3]
They are variable in colour, the colour apparently being determined by their environment and can be pale cream through to greenish-brown, with paler underparts. They can also show irregular markings on the flanks such as dark spotting or horizontal stripes. In the breeding season the males are brighter as their dorsal, anal and caudal fins develop a red colour and have black margins and the pelvic fins and the area around the anus become black.[4] These fish attain a maximum total length of 8 centimetres (3.1in) but are more commonly recorded at standard lengths of around 6 centimetres (2.4in).[2]
Southern pygmy perch are found in a wide variety of freshwater habitats so long as they have aquatic vegetation. They can be found in both still or slow flowing waters and they have been recorded in low current streams, lakes, billabongs, ditches, impoundments, swamps and ephemeralwetlands. In all of these habitat they prefer the vegetated marginal areas.[3]
Southern pygmy perch attain sexual maturity during the first year after hatching, mature males are mature at about 30 millimetres (1.2in) and females at around 33 millimetres (1.3in). The breeding season runs from the late winter into the early spring once the water temperatures rise above 16°C (61°F). Breeding males are territorial and defend a small area of water from other males. The female lays small clutches of eggs in the aquatic vegetation or onto the riverbed within the male's territory. These hatch into larvae of 3-4mm in length 2-4 days after fertilisation.[3]
Conservation
Status
The Millennium drought in the early 2000s affected many species, including the Southern pygmy perch.[5]As of 1995[update] the Southern pygmy perch was relatively common in Tasmania.[6] The fish was once abundant in South Australia,[5] and widespread in New South Wales and in coastal Victoria.[7]
By 2007 it had largely been extirpated from New South Wales, with only three known locations where it was still found: in the Lachlan River catchment, north of Yass; as near Holbrook, and Albury[7] (Tumbarumba?). In 2021 a fourth population was found in the Ooolong Creek in the town of Dalton, by two teenagers.[8][9][10]
As of 2007 the fish was rare in the Murray River catchment of Victoria, and rare and threatened in South Australia.[7] The species was extirpated in the lower Murray in South Australia during the Millennium Drought.[5]
The first shows that it is not listed under the (national) EPBC Act, but is listed as Endangered under the Fisheries Management Act 1994 (NSW) in New South Wales, August 2024 list, and in South Australia is listed as Endangered on the state's "Action Plan for South Australian Freshwater Fishes 2009".[11]
Conservation Advice for the Murray-Darling Basin lineage provided by the Threatened Species Scientific Committee in 2020 was approved by the Minister and published in 2021.[13]
In August 2023, a group of volunteers working with OzFish Unlimited and the local council undertook the translocation of 200 fish to Oolong Creek, to boost the population there.[8]
In the waters of the lower Murray in South Australia, volunteer groups collected fish when they were still naturally occurring there before the waters receded, and placed into dams. In 2025 scientists at Adelaide University and CSIRO have been studying the tiny otoliths of the fish, which provide information about its growth. In September 2025 hundreds of fish were released into a private marina on the shores of the Murray River at Clayton Bay on Lake Alexandrina, hoping to reintroduce the species to the area. The fish releases are funded by the Coorong, Lower Lakes and Murray Mouth (CLLMM) Research Centre,[5]
Taxonomy
The Southern pygmy perch was first formally described in 1861 by Albert Günther with the type locality given as the Murray River.[14] Molecular studies have shown that there are two cryptic species within Nannoperca australis one from the eastern coastal streams and the other from the Murray–Darling basin and the western coastal streams.[3]
Aquarium
The Southern pygmy perch is in the aquarium trade within Australia, where it is kept in cold water aquaria and in ponds.[4]
↑ Paul Humphries (1995). "Life history, food and habitat of Southern Pygmy Perch, Nannoperca australis, in the Macquarie River, Tasmania". Marine and Freshwater Research. 46 (8): 1159–1169. doi:10.1071/MF9951159.
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