Murray Cod
Most of the fish in the Murray-Darling basin are unique to Australia, with the endangered Murray cod (*Macccullochella peelii*), being the best known.
Murray Cod
The heaviest recorded Murray Cod weighed in at a whopping 113 kg, making it Australia's largest freshwater fish. An elder statesmen of the fish world, Murray Cod regularly reach ages of 30-35 years, although it's believed they could live up to 100 - one aspect of its drought-surviving strategy.
Like the Murray-Darling itself, the Murray Cod is in trouble. From being in great abundance at the time of European settlement more than 200 years ago, its numbers are now massively reduced and it's estimated, based on the frequency of fish found in streams, that wild populations have been reduced to about 10 per cent of what they once were. This decline is due to overfishing, rising salinity, habitat destruction by humans and introduced fish such as the European carp, which destroy vegetation, stir up sediment and make water unsuitable for native fish.
Our Murray cod, who goes by the name of Muzz, is wild-bred and has been living at Sydney Aquarium for four years. Because Murray cod are very territorial animals, they can only be kept singly in captivity, and so Murray is the king of his patch. He's fed on a diet of fish and yabbies, similar to what he'd eat in the wild.
In the 1990s a Murray Cod radio-tracking project revealed that in flood times the fish migrate upstream to spawn. Many of the tracked fish travelled 40-50 kilometres from home, but some swam up to 120 kilometres, before returning home to exactly the same part of the river.