Oxleyan Pygmy Perch
Oxleyan Pygmy Perch occur in coastal wallum swamps, streams and lakes between the Mary River in southern Queensland and Coffs Harbour in northern New South Wales. They are also found on Fraser, Moreton and Stradbroke Islands (QLD, NSW).
The Oxleyan Pygmy Perch is a small fish that grows to about 65 mm. Its colour depends on the environment in which it lives and the time of year. In lakes with a sandy bottom and lots of sunlight it is lighter coloured. In small, shaded, deep creeks it can be much darker. The body is a shade of sandy to chocolate brown with darker brown speckling along the middle of the body. At the base of the tail is a small dark brown to black spot. The speckles may give the impression of horizontal bars along the body. The fins are clear, perhaps with a little of the body colour. The belly is lighter because the lining of the stomach cavity can be seen. During the breeding season the colours become much more vibrant, particularly on the male. His body becomes much darker and amongst the darker speckling will be some orange or red spots. The horizontal bars become much more apparent and the fins become almost completely black.
Ecology/Way of Life:
The Oxleyan Pygmy Perch is an elusive species that occurs in heavily vegetated streams, lakes or swamps in sandy areas. Adults are usually found singly or in small numbers amongst roots of bank side trees or clumps of emergent plants. Smaller fish may inhabit more sparsely vegetated areas. The water in these areas is acidic, and darkly stained with organic material. Within its range, water temperatures range from about 12 to 28°C. Spawning occurs throughout the warmer months when water temperatures exceed 20°C. Pairs of fish scatter eggs over vegetation and the substrate. There is no further care of the eggs or fry. The young hatch in 3–4 days and feed on minute invertebrates. Adults mostly eat crustaceans and aquatic insects, but also eat small amount of algae, diatoms, terrestrial insects and fish fry.
Interaction with Humans/Threats:
Oxleyan Pygmy Perch are listed as endangered because of their limited distribution within a highly developed area, a reduction in numbers through habitat destruction and the presence of introduced species such as Damnbusia (Gambusia holbrooki). The wallum habitats are threatened by forestry, agriculture, mining, and urban development. A captive breeding population is presently maintained by Consolidated Rutile Limited, a mining company on North Stradbroke Island. They are not generally kept in aquaria because they require live foods.
Nannoperca oxleyana was named by Whitley in 1940. The name is based on nanna meaning small, perca meaning perch and oxleyana after the explorer John Oxley.
Allen, G. R., Midgley, S. H. & Allen, M. (2002). Field Guide to the Freshwater Fishes of Australia. Western Australian Museum. Perth. 394pp.
Text: Rob Wager & Peter J. Unmack. Distribution map: Peter J. Unmack. Photographer: Neil Armstrong.
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|Distribution of Nannoperca oxleyana|