Clarence river cod
(Maccullochella ikei)

The eastern freshwater cod (Maccullochella ikei), also known as the eastern cod or Clarence River cod, is a large predatory freshwater fish of the genus Maccullochella and the family Percichthyidae, that occur in the coastal Clarence River system of north-eastern New South Wales. Eastern freshwater cod are closely related to the Murray cod of the Murray-Darling River system, and are considered an icon of the Clarence River system.

A long-lived, slow-growing species, eastern freshwater cod are threatened by poaching, habitat degradation, catastrophic natural events such as bushfires, and inbreeding from low genetic diversity. They are currently classified as endangered and protected by law from human exploitation of any kind.

Appearance and size
The eastern freshwater cod is a small to medium-sized grouper-like fish with a deep, elongated body that is round in cross section and a broad, scooped head, and a large mouth lined with pads of very small needle-like teeth. The jaws are equal, or the lower jaw may protrude slightly. The eyes are slightly larger and more prominent than in Murray cod.

The spiny dorsal fin is moderate in height and is partially separated by a notch from the high, rounded soft dorsal fin. Soft dorsal, anal, and caudal (tail) fins are all large and rounded, and are dusky grey or black with distinct white edges. The large, rounded pectoral fins are usually similar in colour to flanks. The pelvic fins are large and angular, set forward of the pectoral fins, and are usually a translucent greyish-white colour, tending toward opacity in large fish. The leading greyish-white coloured rays on the pelvic fins split into two trailing filaments. These filaments are significantly longer than in Murray cod.

Eastern freshwater cod are vary from cream or greyish-white to yellow on their ventral surfaces. Their backs and flanks are usually an intense yellow or gold in colour, overlain with a dense pattern of black to very dark green mottling. The effect is a marbled appearance sometimes reminiscent of a leopards markings. Colouration does vary considerably however and eastern freshwater cod from dark, heavily shaded habitats can be very dark or almost black in colour.

Eastern freshwater cod were historically recorded reaching sizes well over 1 metre in length and up to 48 kg in weight, but today are commonly less than 60 cm in length and less than 5 kg in weight. Large fish are rare today.