In a recent Facebook post someone in the Northern NSW Trout Fishing group (quite an interesting group) said they had caught a fish (see below) and were unsure what it was, and so posted that photo. They soon received a number of replies indicating it was a River Blackfish. I had not heard of them before (I’m sure other HFFishers will have), so looked them up.

Scientific Name:

Gadopsis marmoratus

Other Common Names:

Slippery, slimy, blackfish

Size

Up to 600 mm and 5.5 kg, commonly to 300 mm, fish South of the Great Dividing range, especially in South Eastern Victoria often grow to much larger size than their northern brethren, the two spined
blackfish.

Common in rivers and streams South of the Great dividing Range in Victoria and in higher waters in the South Eastern Murray-Darling basin. Original range extended throughout most of Victoria into south-eastern South Australia (the latter group possibly constituting a distinct taxonomic identity) and at elevations above 600-900 in New South Wales and southern Queensland on the western slopes of the Great Dividing Range.

Now much less common with many areas only holding remnant populations if any. Blackfish are particularly susceptible to siltation in their preferred small upland streams due to their habitat preferences. Common agricultural practice throughout the Murray Darling basin has consequently severely restricted the distribution of this fish.

Diet

Other fish, aquatic insects. An ambush predator.

Habitat

Associated with in-stream cover, rock or wood debris areas providing shelter from high water velocities. Only infrequently encountered in open water or above homogeneous substrates without cover.

History

The size differential between Northern and Southern fish warrants further investigation to determine whether the southern (larger fish) population actually constitute a separate species or sub-species. Some very preliminary work done recently suggest that this may be the case. Another outstanding issue is the question of where to place the Gadopsis genus taxonomically.

Angling

Often overlooked as an angling option, blackfish provide fine sport on light tackle. In some areas, blackfish can reach truly prodigious size, so heavier gear is required at times. Blackfish are generally caught using bait, scrub worms being the best option. Some anglers report success fishing with small, dark coloured lures fished close into creek banks at dusk. Wet flies have also been used with success.

Remember that blackfish are an ambush predator and are secretive rather than shy. The trick is to get your bait or lure to within striking distance of the fish which is generally in heavy cover or lurking under an undercut bank.