Silver Perch

What it is

The silver perch is a ray-finned fish belonging to the terapontid or grunter family. It features a streamlined body that becomes deeper with age, often developing a hump behind the head. Adults display dark grey backs fading to silver sides with a checkered scale pattern and white bellies. The species reaches lengths exceeding sixty centimetres and weights near eight kilograms, though modern wild specimens are significantly smaller. It inhabits the freshwater systems of south-eastern Australia, specifically the Murray-Darling basin.

Where it lives

This species is endemic to the Murray-Darling basin in south-eastern Australia. Historically, it occupied slope and upland reaches of many rivers in this system, extending as far upstream as Cooma on the Murrumbidgee River. Populations have since collapsed across most of this historical range, leaving only one viable self-sustaining group in the central Murray River. Small introductions exist in the Lake Eyre basin and Cataract Dam, but these are not part of its natural distribution.

How it lives

Silver perch are schooling fish that prefer flowing water and act as opportunistic feeders. Their diet consists mainly of insect larvae, molluscs, annelids, and algae, with occasional consumption of small fish. They undertake significant migrations, with recorded movements spanning thousands of kilometres between river sections. These journeys are critical for accessing different habitats throughout their lifecycle, which can extend beyond twenty-seven years.

Breeding and life cycle

Males mature sexually at three years while females require five years. Spawning occurs during late spring and early summer, triggered by water temperatures between seventeen and twenty-eight degrees Celsius. Fish gather at the surface at dusk to release eggs and milt. The resulting eggs are semi-buoyant and drift downstream, hatching within thirty-six hours if they avoid sinking into fine sediment.

Fish and people

Historically, the silver perch was a prized game fish known for its vigorous fight when hooked. Anglers targeted them using worms, shrimps, and lures during summer migrations. The fish also holds cultural significance through Aboriginal names such as bidyan and tcheri. Today, extensive aquaculture farming produces domesticated strains for food and stocking, though these captive populations do not support wild conservation efforts.

Status and threats

The Australian government listed the species as endangered in 2024, following a severe decline from previous abundance. Dams, weirs, and river regulation have blocked migrations and trapped drifting eggs, causing catastrophic population losses. Competition from introduced carp and alien pathogens further threaten survival. Conservationists note that the species requires specific flow conditions and clean substrates for successful recruitment, which are increasingly rare in heavily managed waterways.

Relatives and look-alikes

The spangled perch is another terapontid found sporadically in the northern Murray-Darling Basin. Despite its common name, the silver perch is not related to true perches of the genus Perca. It is the largest member of the Terapontidae family in southern Australian waters, distinguishing it from other regional grunter species.

Questions people ask about Silver Perch

Good reading and sources

• Bidyanus bidyanus on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data