Backyard Aquaponics
A place to discuss aquaponics

Yes, Les thats the one I spoke to. He will have Silvers in a fortnight or so, so I will call him then. I'll probably get 50 first off because I want to minimise the risk of 'dead fish' posts.

I would get IBCs but they wouldnt get though the door of my garden shed.

In Aquariums

Hatchery bred Murray cod are now readily available in aquarium stores in southern Australia. Murray cod are intelligent fish and make immensively attractive, rewarding and responsive aquarium fish. It is widely agreed by everyone who has kept a Murray cod in an aquarium that they are fish with "real personalities".

Watching one of these predatory native fish ambush a live shrimp or fish can be an awe-inspiring display.

Whilst slow growing overall, Murray cod will grow quickly in their first 3–4 years of life, so large tanks are advisable — a minimum of 4 ft in length, and preferably 5 or 6 ft. Murray cod like having structure they can retreat to, so structure such as sunken timber pieces will be appreciated.

Murray cod experience very cold water temperatures in the wild in winter, so they do not need water heaters. A temperature of 24° C however will enable fast (optimum) growth, which given the large size Murray cod reach, is generally not desirable. Some experienced aquarists use water heaters and a temperature of 24° C to grow Murray cod quickly to a size (15–20 cm) where they can be conveniently fed on feeder fish, fish pieces and other foods, whereupon they gradually turn off and remove the water heater to slow growth rates back to normal levels. Conversely, Murray cod are susceptible to extremely high water temperatures — temperatures above 30° C are not recommended, and temperatures significantly above 30° C will cause death. In heatwave conditions in the summer of 2004/2005 a number of aquarists in Australia suffered unfortunate losses as house and tank temperatures soared far above usual levels. Soft drink bottles filled with water and frozen can be used as an emergency measure to reduce tank temperatures.

Unlike many freshwater fish, Murray cod are highly tolerant of salt due to the raised salinity levels they sometimes experience in the lowland reaches of the Murray-Darling Basin during extreme drought. Indeed, common sea salt is a useful tool for keeping Murray cod in tanks, a salinity of 2 grams per litre improves health and keeps most pathogens ("diseases") at bay. Ensure, however, that the sea salt used is free of additives such as iodine and free flow agent.

Caution, and ideally, quarantine procedures, should be used to ensure that feeder fish do not introduce diseases to the tank. With soft skin, Murray cod can be susceptible to white-spot or "ich" and fungal skin infections. At a minimum, disinfect all live food for 1 hour in a 10 gram per litre salt solution before feeding.

Water pH should be kept neutral or slightly alkaline, a pH between 7.0 and 8.0 is perfectly acceptable, 7.0–7.5 is ideal. A small amount of shell grit will provide a buffer against violent pH swings.

A common complaint voiced about small Murray cod in aquariums is that they "hide all day" and "don't show themselves". This is usually only a problem for the first few months of life. Most Murray cod in aquariums, upon reaching a certain size, suddenly gain confidence and then become inquisitive, responsive and rewarding aquarium fish.