It’s a funny thing, life. Once in a while something you see every day can just stop you in your tracks. It’s like a moment of realization that what you are looking at is really, really amazing, and it happened to me recently when I walked past our Murray cod tank.

Muzz our Murray cod has been living here at Sydney Aquarium for about 5 years now, and several times a day I walk past his tank and check things: is he looking OK; are the pumps running; the airstone bubbling; lights working – all the things you get caught up in as an aquarist caring for the critters here at the aquarium. In fact it’s easy to get so caught up in the husbandry side of things that you can forget to simply step back and actually SEE the amazing animals that have their homes here.

And that is what happened the other day. Muzz was sitting at the front of his tank and it suddenly struck me how truly, jaw-droppingly awesome these creatures are.

Muzz is a big fish. We estimate his weight to be about 25kg, which, impressive as he is now, means he has a fair bit of growing to do to reach the maximum size of over 110kg. Yes, that’s right, 110 kg, which makes the Murray cod far and away Australia’s largest freshwater fish – more than twice the size of the next largest, the barramundi.

We’re  expecting him to be here for a while too. Murray cod live a long time and while we’re not exactly sure how old Muzz is, the weight of a wild fish in kilos usually approximates the age in years. For example, a 5kg fish will be five years old. The oldest fish accurately aged was 48 years old, 1.3m long and 32.5kg so it’s likely that given the chance they get much older than this! They can, however, grow much more rapidly than a kilo per year, and as Muzz has had a pretty easy life at the aquarium with lots of food, he is probably quite a bit younger than his weight would suggest.

And talking of food Muzz loves a good feed. In the wild Murray cod are “sit-and-wait” predators, meaning they will wait around hiding under their favourite snag (a rock or fallen log, not a sausage) until a meal swims within easy reach. Then, with a powerful flick of the tail and a gulp of the massive mouth – which has to be seen to be believed – they catch their prey.

Food comes in all shapes and sizes for the Murray cod and favoured items change as the fish gets bigger. Fish and yabbies form the main part of the diet, but they will opportunistically take other prey, including frogs and even ducklings.

Murray cod fossils from 26 million years ago are found in NSW, although it is possible they have been around as long as the Murray-Darling basin itself – between 50-60 million years. With such an ancient lineage, Murray cod naturally feature in Aboriginal Dreamtime legends; the Ngarrindjeri people have a story which tells that the Murray River itself was dug by a huge Murray cod escaping from a small creek when chased by a hunter, an indication of the respect commanded by the huge, powerful fish.

Muzz originally came to us from NSW Fisheries in Narrandera through their Murray cod restocking program. Murray cod historically were found pretty much throughout the warmer areas of the Murray-Darling drainage system, but they now face a number of threats including habitat degradation and competition from introduced species. The restocking program is helping to boost the natural population of this magnificent fish.

Here at Sydney Aquarium Muzz lives in the first tank and is the first fish to greet visitors, and what an impressive introduction to our underwater journey he is. Come in and meet Muzz, king of freshwater fish and the monarch of the Murray-Darling!

(PICTURE COMING SOON!)