Southern Pygmy Perch
The Southern Pygmy Perch, Nannoperca australis, is native to the Lachlan, Murrumbidgee and Murray River systems, as well as coastal streams in South Australia, Victoria, north-eastern Tasmania and King and Flinders Islands in Bass Strait. It is also called the Tasmanian Pygmy Perch.
The population of this fish has fallen rapidly in most parts of its range and it is listed as endangered in New South Wales.
Length and Longevity
This fish can grow to about 8.5 cm (between 3 and 4 inches) long, but most only get to 6cm (2.5 inches). They become sexually mature in their first year and can breed in the first spring after hatching. At this time the males will be about 3 cm and the females about 3.3 cm.
They can live up to at least 5 years, but many fish will die long after only one or two years.
The Southern Pygmy Perch has a small mouth reaching to just below the eye, and a rounded tail. Their colour varies depending on their habitat and other environmental conditions and can vary from pale cream to green-brown, with paler bellies. Individuals may also have irregular markings on their sides including dark spots or longitudinal bands.
Breeding males have brighter colours, with the dorsal, caudal and anal fins becoming bright red with black edges, and with the pelvic fins and region around the vent turning black.
The Southern Pygmy perch is a temperate water species and in the wild survives water temperatures from 4 degrees C (39 degrees F) to over 30 degrees C (86 degrees F). In an aquarium, the temperature can vary between 10 degrees C (50 degrees F) and 30 degrees C (86 degrees F). This means that they are most suitable for unheated aquariums but can also live in heated aquariums with selected tropical fish.
They come from a wide range of habitats from the mighty Murray Darling River system and billabongs to tiny drains, irrigation channels, ditches and swamps. The pH and salinity of these waters vary enormously and this fish can survive a wide range of pH and hardness.
In the wild they live near the margins of streams, billabongs, drains, dams and swamps in still or gently flowing water with a lot of plants, both in the water and frequently overhanging trees.
They mostly avoid open water and prefer a very well planted aquarium or pond.
In the wild The Southern Pygmy Perch is mostly carnivorous, eating mainly small invertebrates like mosquito larvae and other insects and their juvenile forms, as well as Daphnia and other crustaceans. As the fish grow bigger they are better able to eat whole insects like mayflies. Naturally they could eat baby fish, but fish do not appear to be a major part of their diet. They have a small mouth well adapted to eating small creatures like wrigglers.
In the aquarium, the best food is live food like wrigglers and Daphnia supplemented by frozen blood worms or dried black worms etc. They eat normal fish food readily but most dried fish foods are intended for omnivorous fish and are not ideal for this fish as the only food, and the fish will benefit from live or frozen food such as blood worms.
The Southern Pygmy Perch seems to do better in schools, and in the wild spend most of their time in small loose schools. They are a peaceful community fish and will live with other peaceful fishes of a similar size. They can be kept in a temperate or a cold-water aquarium with small goldfish and other cold-water fish of a similar size. In a tropical aquarium, they will be all right with the thermostat set at 24 degrees C (75 degrees F) with many types to tropical fish. You will need to avoid putting them with large or very aggressive fish.
In the wild these fish breed frequently from September to January when the water temperature is above 16 degrees C (61 degrees F). A rising water temperature seems to stimulate spawning. While breeding, the males become territorial. At each spawning the females will lay between 50 and 1000 eggs each. The eggs absorb water after being laid and then are about 1.2 to 1.4 mm in diameter. The eggs are round and not adhesive and are usually laid over plants. They hatch in 2 to 4 days and the newly hatched fry are 3 to 4 mm long.
The baby fish start off eating microscopic things like protozoa (infusoria) before graduating to tiny planktonic invertebrates like Daphnia.
This fish will spawn in an aquarium.
The Southern Pygmy Perch is a superb fish for mosquito control in ponds. In its native range, as long as local laws permit, in many circumstances it is the mosquito control fish of choice. It is far superior to the so called ‘Mosquito Fish’ of the genus Gambusia that have displaced them in many places.
In New South Wales this fish is endangered and it is illegal to catch and keep, buy, sell, possess or harm Southern Pygmy Perch (or any other threatened species in NSW) without a specific permit, licence or other appropriate approval, and significant penalties apply. For endangered species, these penalties can include fines of up to $220,000 and up to 2 years in prison. For more details about this contact the New South Wales Department of Primary Industries. Restrictions also apply in South Australia and Tasmania.
The Southern Pygmy perch sold in Betta Trading and in many other shops are bred in captivity and can be bought and sold without restriction.
Many people like to have frogs breeding in their gardens. These harmless amphibians are not only an important part of the native ecology of southern Australia but they also help to control insect pests. Goldfish or Koi ponds are usually a very poor place for frogs to breed because larger fish like goldfish and Koi eat the young tadpoles.
If you have no fish you are setting up a mosquito breeding pond as well as a frog pond. The Southern Pygmy Perch is one of the fish that will eat mosquito larvae but mostly not the frogs, tadpoles or frog eggs. Other fish that are used include the River Murray Rainbow Fish and the White Cloud Mountain Minnow. Some people consider that the River Murray Rainbow Fish is too aggressive towards the tadpoles and prefer smaller fish like the Southern Pygmy Perch.
The IUCN Red List has not evaluated the risk of this fish becoming extinct in the near future. It is officially considered threatened in New South Wales and there are major legal protections for the Southern Pygmy Perch in that state. Both government and non-government organisations are working at preserving the fragmented population there.
It is listed as endangered in South Australia and is protected here and major efforts are being made to prevent its extinction in South Australia.
In all parts of its mainland range there have been huge reductions in the numbers of this fish.
It is also native to the streams of northern Tasmania which drain towards the north as well as King and Flinders Islands. In Tasmania, it is illegal to catch this fish without a permit, and other restrictions may apply
This fish is threatened particularly by the destruction and fragmentation of its former habitats. This destruction is caused both by direct human action in clearing trees and other vegetation and by grazing animals. In the water, the introduction of carp to eat the water plants has caused a drastic reduction of the best habitat for the Southern Pygmy Perch.
Another problem this fish faces is the introduced Trout and Redfin Perch which eat the Southern Pygmy Perch. Competition with Gambusia also causes problems. Gambusia (mosquito fish) were introduced in the mistaken belief that they are good for controlling mosquitoes. Mosquito larvae only make up about five percent of the diet of the mosquito fish, but twenty percent of the diet of many other fish like the Southern Pygmy Perch. Gambusia also attack other fish, harrying them and nipping their fins.
There are genetically distinct populations of the Southern Pygmy Perch, in particular an eastern and a western population which some researchers believe should be accorded the status of separate species.
This species has several relatives living in other parts of Australia, often with ranges overlapping. These include
Nannoperca obscura (Klunzinger, 1872) (Yarra pygmy perch)
Nannoperca oxleyana Whitley, 1940 (Oxleyan pygmy perch)
Nannoperca pygmaea D. L. Morgan, Beatty & M. Adams, 2013 (little pygmy perch)
Nannoperca variegata Kuiter & G. R. Allen, 1986 (golden pygmy perch or Variegated Pygmy Perch or Ewen’s Pygmy Perch) This species is listed as vulnerable in the IUCN Red List but information from Victoria suggests it is in serious danger of extinction.
Nannoperca vittata (Castelnau, 1873) (western pygmy perch)
Nannoperca balstoni (Balston’s pygmy perch)
Nannoperca australis is called the Southern Pygmy Perch, the Swamp Perch or the Tasmanian Pygmy Perch in English, Austraalia pisiahven in Estonian, Südaustralischer Zwergbarsch in German and 澳洲矮鱸 or 澳洲矮 鲈 in Mandarin Chinese.
Nannoperca australis ( Günther, 1861 ) is its official scientific name. Paradules leetus (Klunzinger, 1872), Nannoperca riverinae (Macleay, 1881), Microperca tasmaniae (Johnston, 1883) and Nannoperca australis flindersi (Scott, 1971) are junior synonyms.
Any fish can disrupt an ecosystem it is not native to and if you are keeping the Southern Pygmy Perch in an area it does not come from naturally great care should be exercised to prevent its escape.
Sources and Picture Credits
New South Wales Department of Primary Industries Southern Pygmy Perch Nannoperca australis November 2013 Primefact 190 Second Edition Fisheries Ecosystems Unit, Port Stephens Fisheries Institute. Other publications of the New South Wales Department of Primary Industries.
The IUCN Red List of Threatened Species.
Riverspace Pudman Creek Protection and Restoration.
Victorian Department of Sustainability and Environment Variegated (Ewen’s) Pygmy Perch action statement.
Adelaide and Mount Lofty Ranges threatened species profile.
Atlas of Living Australia
history, food and habitat of southern pygmy perch, Nannoperca australis,
in the Macquarie River, Tasmania by P Humphries in Marine and Freshwater
Research 46(8) 1159 - 1169
S.J. and Adams, M. (2013) Nannoperca pygmaea, a new species of pygmy
perch (Teleostei: Percichthyidae) from Western Australia. Zootaxa, 3637
(4). pp. 401-411. Murdoick University Library.