Twospine Blackfish
Gadopsis bispinosus
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Quick Facts
Distribution
Interesting Info
- The Twospine Blackfish is a small, secretive freshwater fish found in the upland rivers and creeks of southeastern Australia, mainly in Victoria and southern New South Wales.
- It gets its name from the two spines at the front of its dorsal fin, which help distinguish it from the closely related River Blackfish (Gadopsis marmoratus).
- They are generally slim-bodied compared to River Blackfish, with olive-brown to dark grey colouring and fine mottling that blends perfectly with cobbles and leaf litter on stream beds.
- They prefer cool, clear, fast-flowing upland streams with rocky bottoms, boulders, and woody debris that provide plenty of hiding places.
- Twospine Blackfish are mainly nocturnal ambush predators, feeding on aquatic insects, crustaceans, and sometimes small fish.
- Historically, they were more widespread, but now their distribution is patchy and fragmented, restricted to certain tributaries of the Murray–Darling Basin and nearby upland catchments.
- They are considered poor dispersers, rarely moving far from their home pools, which means local populations are easily isolated.
- Breeding occurs in spring and early summer (October–December) when water temperatures rise. Females lay adhesive eggs under rocks or in crevices, and males guard the eggs until they hatch.
- Their young grow slowly and take 2–3 years to mature, which makes populations vulnerable to sudden environmental changes.
- Lifespan is surprisingly long for a small fish: individuals can live for 8–12 years, provided they survive predation and habitat disturbances.
Species Interaction
Recreational Fishing, Conservation
Twospine Blackfish have little direct contact with people outside of scientific monitoring and conservation programs. They are not a fishing target, but their presence is important to anglers because healthy blackfish populations indicate cold, clean, well-structured streams. Their survival depends on ongoing habitat protection, sediment control, and management of introduced trout that compete with or prey on them. They are often caught as bycatch from anglers targeting other species.
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Percichthyidae
Genus: Gadopsis
Species: Gadopsis bispinosus
Conservation Status
In Australia, the Twospine Blackfish is not currently listed as a threatened species under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999, but it is listed as a threatened species in Victoria, where it is considered vulnerable to extinction. They are also considered to be a species of conservation significance in the ACT and is protected under the Nature Conservation Act 2014. The species is listed as vulnerable to extinction in the ACT, which means that it is at risk of becoming endangered in the near future.
How to catch
Twospine Blackfish
Catch Difficulty: Difficult
Tackle: Running sinker rig, Artificial lure
Bait: Hard-body lures, Worms, Insects, Flies
Technique: Slowly sink bait toward the bottom, Retrieve lures slowly
Popularity: Mostly caught as bycatch
