Yarra Pygmy Perch, Nannoperca obscura (Klunzinger 1872)


Yarra Pygmy Perch, Nannoperca obscura. Source: Tarmo Raadik. License: All rights reserved

Summary:

A small dusky, pale brownish-grey or olive-green pygmy perch becoming pale below, with darker chevron-shaped markings on the rear of the body, transparent to pale yellowish to blackish fins, and a pupil that is somewhat oblong. The Yarra Pygmy Perch differs from other Nannoperca species in having the pre-orbital bone not completely covered by skin, exposing its serrated lower edge. 

The species was described from the 'Yarra Lagoon, near Melbourne'. Unfortunately, Yarra Pygmy Perch are now extinct in the Yarra River.


Cite this page as:
Bray, D.J. & Thompson, V.J. 2020, Nannoperca obscura in Fishes of Australia, accessed 05 Dec 2020, http://136.154.202.208/home/species/4459

Yarra Pygmy Perch, Nannoperca obscura (Klunzinger 1872)

More Info


Distribution

Endemic to temperate waters of the Bunyip River system, Victoria, westwards to the Finniss River, Bool Lagoon and Lake Alexandrina in eastern South Australia.

Populations that once inhabited the Yarra River and Dandenong Creek near Melbourne, are now presumed extinct. Remaining populations have become fragmented due to water regulation and habitat loss.

Typically inhabits slow-flowing to still waters with abundant submerged and emergent aquatic vegetation, and often woody debris - such as lakes, ponds, , along with pools in slow to moderately high-flowing rivers and streams. 

Features

Dorsal fin  VIII-IX, 7-9 (usually IX, 9); Anal fin III, 6-7; Pectoral fin 11-13 (usually 12).

Body oblong, compressed; dorsal profile more strongly arched than ventral profile; head large, dorsal profile straight; snout pointed; eye of moderate size, dorsolateral; mouth small, terminal, slightly oblique, protractile; jaw reaches back to front of eye; jaws, vomer and palatines with narrow bands of villiform teeth; lower, free edge of preorbital bone straight, strongly serrated; numerous distinct pores on head and operculum.

Scales moderately-large, finely ctenoid without circular ridges; scales present on head, opercula and cheeks; lateral line of interrupted series of tubed scales; mid-lateral scales 28-30; transverse scale rows 12-13.

A single dorsal fin with an anterior spiny section and posterior soft section separated by deep notch; anal fin opposite and similar to soft part of dorsal fin; pectoral fins small, rounded, positioned low on sides; ventral fins small, pointed, set well forward on abdomen; caudal fin moderately large, truncate or rounded.

Size

To 7.5 cm SL, commonly to 5cm.

Colour

Olive green above, greenish-brown laterally, yellowish-white below, with darker scale margins and a faint reticulate pattern. Opercular region with golden sheen. Several dark blotches mid-laterally. Fins clear, fawn to orange, often with dark margins; pelvic and anal fins often with dark anterior edge. Caudal peduncle with a dark spot.
Prior to spawning, the pelvic fins of the male become black, the leading edge of the anal fin darkens and the dorsal and anal fins become an intense brownish-orange.

Feeding

Feeds mostly on insects, insect larvae and planktonic crustaceans. The species may also consume small molluscs.

Biology

Little is known of the biology of this species. Spawning occurs in September to October at water temperatures between 16 and 24°C. Like other pygmy perches, this species presumably spawns large demersal eggs amongst aquatic vegetation.

The species is short-lived, with individuals living less than 5 years.

Conservation

IUCN Red List: Endangered

EPBC Act 1999: Vulnerable

Victorian Flora and Fauna Guarantee Act 1988: Threatened

Populations of Yarra Pygmy Perch have declined in recent decades, due to habitat loss and predation by, and competition with introduced species such as Redfin (Perca fluviatilis) and Brown Trout (Salmo trutta).

Major threats include habitat degradation and loss, altered flow regimes; predation by Redfin Perch, Perca fluviatilis, Brown Trout, Salmo trutta and Rainbow Trout, Oncorhynchus mykiss; habitat destruction by Common Carp, and competition and predation by Eastern Gambusia, Gambusia holbrooki; affects of climate change

Remarks

Yarra Pygmy Perch form small shoals, often mixing with Southern Pygmy Perch, Nannoperca australis.

Similar Species

The Yarra Pygmy Perch differs from the Southern Pygmy Perch, Nannoperca australis, in having a smaller mouth, a serrated preorbital bone, and in having a slightly notched pupil rather than one which is round. Fins of breeding males turn black compared with the bright red fins of N. australis.

Etymology

The specific name obscura is from Latin (= darkened) in reference to the dark fins of breeding males.

Species Citation

Paradules obscurus Klunzinger, 1872, Arch. Naturg. 38(1): 20. Type locality: Yarra lagoon, Melbourne, Victoria.

Author

Bray, D.J. & Thompson, V.J. 2020

Resources

Atlas of Living Australia

Australian Faunal Directory

Catalog of Fishes

Yarra Pygmy Perch, Nannoperca obscura (Klunzinger 1872)

References


Allen, G.R. 1989. Freshwater Fishes of Australia. Neptune, New Jersey : T.F.H. Publications 240 pp., 63 pls. 

Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field Guide to the Freshwater Fishes of Australia. Perth : Western Australian Museum 394 pp.

Brauer, C.J., Unmack, P.J., Hammer, M.P., Adams, M. & Beheregaray, L.B. 2013. Catchment-Scale Conservation Units Identified for the Threatened Yarra Pygmy Perch (Nannoperca obscura) in Highly Modified River Systems. PLoS ONE 8(12): e82953. DOI: 10.1371/journal.pone.0082953

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

Cadwallader, P.L. & Backhouse, G.N. 1983. A Guide to the Freshwater Fish of Victoria. Melbourne : F.D. Atkinson Government Printer 249 pp. figs. (as Edelia obscura)

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Castelnau, F.L. de 1872. Contribution to the ichthyology of Australia. 1. The Melbourne fish market. Proceedings of the Zoological and Acclimatisation Society of Victoria 1: 29-242 1 pl. (described as Microperca yarrae)

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Klunzinger, C.B. 1872. Zur Fische-fauna von Süd Australien. Archiv für Naturgeschichte 38(1): 17-47 pl. 2 (p. 20, as Paradules obscurus) See ref at BHL

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McDowall, R.M. (ed.) 1980. Freshwater Fishes of South-eastern Australia. Sydney : A.H. & A.W. Reed 208 pp., figs, 32 pls. 

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Saddlier, S. & Hammer, M. 2010. National Recovery Plan for the Yarra Pygmy Perch (Nannoperca obscura). East Melbourne, Victoria: Department of Sustainability and Environment. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/recovery/yarra-pygmy-perch.html.  

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Quick Facts


CAAB Code:37323007

Conservation:EPBC Vulnerable: SA Critically Endangered

Conservation:IUCN Endangered

Habitat:Freshwater

Max Size:7.5 cm SL

Native:Endemic

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