Scientific Name
Nannatherina balstoni

Common Name
Balston's pygmy perch

Biology
Is the rarest of all the endemic freshwater fishes of southwestern Australia. Inhabits coastal streams, lakes, ponds and swamps, where the water is dark and acidic (pH as low as 3.0) and has a large seasonal fluctuation in temperature (11-30?C) (Ref. 27892, 44894). Favors shallow water and is commonly found in association with tall sedge thickets (Ref. 44894). Larva feeds mainly on cladocerans, copepods and dipteran larvae, while juveniles and adults ingest mostly terrestrial fauna (Ref. 6398, 44894). Breeds in the middle of winter in response to flooding. Female lays between 500-1600 eggs each. The majority of adult perishes shortly after spawning at the end of their first year (Ref. 44894). Both male and female attain sexual maturity at the end of their first year of life when they have attained an average TL of 6.0 and 6.3 cm respectively (Ref. 27892).

Classification

Classified By

Regan, 1906

Class

Ray-finned fishes (Actinopterygii)

Order

Perch-like fish (Perciformes)

Family

Temperate perches (Percichthyidae)

Distribution

Region

Oceania

Distribution

Oceania: coastal drainages of southwest Australia between Two People Bay (near Albany) and the Blackwood River. Also reported from the Goodga River to Gin Gin Brook, western Australia (Ref. 7300).

Range

31°S - 34°S

Environment

Climate

Temperate

Water Temperature From

15 °C

Water Temperature To

30 °C

Depth From - meters

Unknown m

Depth To - meters

Unknown m

Zone

benthopelagic

Environment

Freshwater; ; pH range: 6.0 - 6.5; dH range: 5 - 10 benthopelagic

Trophic Level

3.38 s.e. 0.38 Based on diet studies.

Occurs in Marine / Salt water

False

Occurs in Brackish water

False

Occurs in Fresh Water

True

Occurs on Reefs

False

Is kept in Aquariums

True

Physical Size and Genetics

Maximum Length

9.0 cm

Common Length

6.0 cm

Phylogenetic Diversity Index

PD50 = 1.0000 many relatives (e.g. carps) 0.5 - 2.0 few relatives (e.g. lungfishes)

Human Uses and Population

Human Uses

Fisheries: of no interest; aquarium: commercial

Vulnerability

Low vulnerability (11 of 100)

Resilience

Medium, minimum population doubling time 1.4 - 4.4 years (tm=1; K=1.31-1.69; Tmax=3; mean Fec=1243;)

Threat To Humans

Harmless

IUCN Red List Status

Data deficient (DD)