Little Pygmy Perch, Nannoperca pygmaea Morgan, Beatty & Adams 2013


A Little Pygmy Perch, Nannoperca pygmaea, from the Mitchell River, southwest Western Australia. Source: David Morgan / Freshwater Fish Group & Fish Health Unit, Murdoch University. License: All rights reserved

Summary:
A very small pygmy perch found only in the Hay and Mitchell river systems of south Western Australia. This species may be Australia's rarest freshwater fish.

Cite this page as:
Bray, D.J. 2020, Nannoperca pygmaea in Fishes of Australia, accessed 15 Jul 2020, http://136.154.202.208/home/species/4864

Little Pygmy Perch, Nannoperca pygmaea Morgan, Beatty & Adams 2013

More Info


Distribution

Found only four catchments in the south west coastal region of Western Australia: Hay River, Mitchell River, Denmark River and the Kent River systems. 
Inhabits permanent refuge pools during summer months - usually shallow tannin stained, acidic streams with stands of the paperbark Melaleuca rhaphiophylla. The waters of the catchment have increased salinities.

Feeding

Feeds on the aquatic larvae of terrestrial insects, and tiny crustaceans (copepods and ostracods).

Biology

Spawns in the middle of year year with a peak in July-August. The species is potamodromous, and individuals migrate upstream into tributaries during early winter when stream flows increase. The Little Pygmy Perch is a serial batch-spawner, with females releasing multiple batches of eggs, most likely amongst inundated vegetation.

Conservation

IUCN : Endangered
Major and potential threats include increased salinity, decreased water flows due to climate change, water extraction for agriculture, increased nutrient levels and sedimentation from agriculture and forestry, and predation by introduced fishes.

Similar Species

Differs from the Western Pygmy Perch, Nannoperca vittata, in having narrow stripes on the lower sides, generally fewer dorsal-fin and anal-fin rays, a more pronounced spot (ocellus) surrounded by a halo at the termination of the caudal peduncle, and in lacking dark pigment on the underside before the anus and having no distinct pigment on the hind margin of the scales on the caudal peduncle.

Differs from Balston's Pygmy Perch, Nannatherina balstoniin having an exposed rear edge of the preorbital (vs. hidden under skin), fewer transverse scale rows (13 vs. 15–16), a small mouth (rarely reaching eye vs. reaching well beyond eye), ctenoid (vs. cycloid) body scales, generally fewer pectoral rays and smaller maximum size. (Morgan et al. 2013)

Etymology

The specific name is from the Latin pygmaeus (= dwarf) in reference to this being the smallest species of pygmy perch.

Species Citation

Nannoperca pygmaea Morgan, Beatty & Adams 2013, Zootaxa 3637(4): 3, Fig. 2A. Type locality: Hay River, Western Australia, 34°53.28'S, 117°29.45'E.

Author

Bray, D.J. 2020

Resources

Atlas of Living Australia

Little Pygmy Perch, Nannoperca pygmaea Morgan, Beatty & Adams 2013

References


Allen, M.G. 2016. Barriers to fish migration in drying climates: contributions from south-western Australia. PhD thesis, Murdoch University, Perth. http://researchrepository.murdoch.edu.au/id/eprint/33737

Allen, M.G., Morgan, D.L., Close, P.G. & Beatty, S.J. 2020. Too little but not too late? Biology of a recently discovered and imperilled freshwater fish in a drying temperate region and comparison with sympatric fishes. Aquatic Conservation: Marine and Freshwater Ecosystems https://doi.org/10.1002/aqc.3346

Beatty, S., Close, P., Morgan, D., Allen, M., & Lawrence, C. 2015. Conserving freshwater fish in south-west Western Australia: A summary of distribution, migration, critical habitats and threats to the region’s most endangered freshwater fishes. A report for the State Natural Resource Management Office, Western Australia. Project No. 12035, 40 pp.

Beatty, S. & Morgan, D.L. 2019. Nannoperca pygmaea. The IUCN Red List of Threatened Species 2019: e.T122906197A123382291. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T122906197A123382291.en. Downloaded on 20 June 2020.

Beatty, S.J., Morgan, D.L. & Lymbery, A.J. 2014. Implications of climate change for potamodromous fishes. Global Change Biology 20: 1794-1807.

Buckley, S.J., Domingos, F.M.C.B., Attard, C.R.M., Brauer, C.J., Sandoval-Castillo, J., Lodge, R., Unmack, P.J. & Beheregaray, L.B. 2018. Phylogenomic history of enigmatic pygmy perches: implications for biogeography, taxonomy and conservation. Royal Society Open Science http://doi.org/10.1098/rsos.172125

Morgan, D.L., S.J. Beatty & M. Adams. 2013. Nannoperca pygmaea, a new species of pygmy perch (Teleostei: Percichthyidae) from Western Australia. Zootaxa 3637(4): 401–411. (Abstract)

Quick Facts


Conservation:IUCN Endangered

Habitat:Freshwater

Max Size:4 cm SL

Native:Endemic

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Species Maps

CAAB distribution map