River blackfish

The river blackfish, a freshwater species endemic to southeastern Australia, inhabits regions from southern Queensland to central Victoria. It thrives in the Murray-Darling river system and some coastal waterways. Historically, this fish coexisted with species such as the Murray cod and golden perch in lowland and midland areas, and with trout cod and Macquarie perch in upland regions. Among anglers, the river blackfish is a prized catch within its range.

Physically, the river blackfish is characterized by an elongated, rounded body, a distinct snout, a large mouth, and small to moderate-sized eyes. These ambush predators primarily hunt at night, feeding on crayfish, shrimp, small fish, and aquatic insects. In the Murray-Darling river system, they typically grow to about 30 cm in length, although some individuals in coastal drainages can reach up to 60 cm.

Interestingly, the river blackfish has managed to traverse the Great Dividing Range through natural river capture events, resulting in a population known as the southern river blackfish, which can grow significantly larger than their Murray-Darling counterparts. Some researchers even propose that river blackfish populations from different regions of the Murray-Darling system might constitute distinct species or subspecies.

Conservation efforts are imperative for the river blackfish due to several threats, including overfishing, habitat degradation from siltation and removal of snags, and competition from introduced trout species. The bushfires of the early 2000s heightened concerns, as increased siltation and altered habitats may lead to greater predation levels by invasive trout species. In South Australia, river blackfish are classified as a protected species due to these vulnerabilities.