Colour ranges from grey to brown dorsally or laterally, usually mottled with dark brown to black blotchings with a whitish underbelly. Larger fish have less mottlings and can be more green in colour fading to white below. It builds a nest in areas of still water to breed, and its reproduction is not temperature reliant. Catfish feed on zooplankton, small fish, shrimps and insects. Catfish are relatively inactive and do not migrate for spawning, unlike other inland species such as trout, golden perch or Murray cod.
Can grow up to 900 mm and 7 kg, however fish over 2 kg are exceptional.
Freshwater Catfish (also known as Eel-Tailed Catfish) were formerly very abundant across most of the Murray-Darling Basin in inland NSW. Prior to the 1980s, they provided recreational fishing opportunities and they are still considered one of the premier table fish by many country people. However, catfish numbers declined substantially following the invasion of carp during the 1970s and 80s. In addition to carp, thermal pollution and season flow reversal also have major impacts in affected reaches. Catfish have virtually disappeared from the Murray, Murrumbidgee and Lachlan catchments. Catfish are still relatively common in parts of the Macquarie, Namoi, Gwydir and Border River catchments and coastal catchments North of Newcastle.
Freshwater Catfish in the Murray-Darling Basin are listed as an endangered population in NSW.
Recent electrophoretic studies of proteins of some more northerly populations indicate that catfish inhabiting coastal rivers from the Manning to the Belliger Rivers may be of different species and those from the Nymboida River (Clarence River system) northwards to at least the Tweed River subspecies, different from the widespread inland form.