Two-spined blackfish

The two-spined blackfish (Gadopsis bispinosus) is a species of temperate perch endemic to Australia.

It is found in the cool, clear, strong-flowing, cobble bottomed, sub-alpine rivers and streams (ranging from small to large) in the southeast corner of the Murray-Darling river system. Their range encompasses northeast Victoria, southeast New South Wales and the Australian Capital Territory. Originally two-spined blackfish co-inhabited many of these waters with Macquarie perch and trout cod.

Two-spined blackfish are similar in shape and appearance to river blackfish, though their spiny dorsal fin usually contain only two spines (hence their scientific name) in comparison to river blackfish which have 7 to 13 distinguishable spines in their spiny dorsal fin. (In reality, this is a rather academic point as two-spined blackfish have blurred the difference between the dorsal spines and the dorsal rays that make up their soft dorsal fin, and any distinctions between the two weakly calcified dorsal spines and the dorsal rays that follow it are hard to pick in a living specimen.)

The two-spined blackfish is similar to the river blackfish in spawning and diet; however, they prefer rocks and the interstices ("gaps") between to timber as the main spawning and habitat sites. Two-spined blackfish are also much smaller, commonly 15 to 17 cm and a maximum size of 30 cm. Two-spined blackfish breed between October and December. Larvae hatch after around 16 days and remain at the spawning site with the male parent for another 3 weeks.