Backyard Aquaponics
A place to discuss aquaponics

Mate I'm not having any problems with them. Touch wood. Keeping your water temps above 25 seems to be a bit extreme! My water temps have varied greatly since I picked them up in Dec. Water temps at the moment are about 24c but they have been just as happy with water temps around 17.

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Yep mine are in an aquarium waiting for ap space, and its temp varies a lot. I am down to about 12 out of the 30 I started with but the deaths were my fault. I wasnt prepared to get fry, when told they were yearlings hmmm
Any hoo, they grow like crazy, well some of them, and others not so much, due to pecking order by my reckoning of watching them in the aquarium.
I will be putting them in the greenhouse tank when I harvest the jades, and any small jades can stay in with them.

Thanks for the comments. For the moment I'll keep them at a constant temperature (around 25 degrees) until they are a bit bigger >120mm and slowly reduce the temperature to match the SP tank and see how they go. Following this if they don't start falling over I'll join the two systems back together. The aquaponics system temperature does not fluctuate greatly due to the water volume +4000 litres with the tanks in the shed and the grow beds in the attached bush house, however the temperature is usually around 18-20 degrees and only on really hot days does it get above 22 degrees with the highest recorded water temp at 25 degrees (over 18 months of data). This was following days of +30 degree temperatures. The SP handle the temperature changes with no problem with temperatures down to 10 degrees. Any other ideas on why when the murray cod temperature drops the mortality rate rises?

Mate it sounds to me like your experiencing the opposite result to what I have experienced.
I found the SP would die on me and/or stop feeding when temps fluctuated. Yet I am not having any issues at all with MC.

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Still no water temp issues with my MC, water temps are down to 11 and may have been lower at times, they are even still eating at 11 however I am not feeding them regularly at the moment since I figured they would not eat with water temps so low. Looks like i'm wrong.

Have not lost any recently since bringing my salt level back up. Would estimate I would still have 45 out 50 still. Some have grown suprisingly well other have not.

My water temp is at about 16 degrees and they are doing fine, I took the murray cod out of the floating container which kept them crowded and let them go in the 1000 liter tank not long after my previous post. This tank and the SP 2000 liter tank are now connected and cycling to the grow beds. I had not lost a MC until Friday, it had a distinct bit mark half way only its body. They are feeding, however I have reduced feeding to twice a day. The biggect MC is about 120mm and look to be growing faster than the SP. We had one of the SP for lunch a few weeks ago and I was disappointed with the muddy taste. I now have an old bath tub and will clean them out in 0.5% salty water for a week and give them another go.

Do you have any form of hide in the tank for the MC's.. I have a whole heap of cut of pieces of pipe for my Cod to hid in..

That give the smaller fish a chance to hide from the others..

Also my water temps are about 14 degrees and getting colder..

Juergen

I only have the pump 1200l/hr which continually circulates water through the filter (90l container with 4 layers of matala mat) to remove solids out of the tank and keeps the nitrogen cycle happening even if the tank is not connected to the grow beds. The points was to try and keep them crowded and well fed to prevent them eating each other and be able to catch them if they show signs of having fungal infections, to give them a salt bath. I have not had to salt bath them for at least a month and have not added any salt to the water since then which seems to be the norm for keeeping MC and they seem fine so far. The MC with the bite mark was about average size and I can't be sure if this occurred after it was sick or if this was the cause?

Got mine out into the greenhouse system a few weeks ago. Only 9 left out of 30 but most of the deaths were from being unprepared when I first got them.
They are eating but not a lot and only if I feed them in the evening when the water is warmest

Murray Cod are definitely fragile in an aquaponics system in my opinion they are prone to stress due to environmental changes; pH swings, ammonia levels, temperature and predation especially when they are young. My system is over two years old, the plants are growing well and the water chemistry is stable, I have to add lime daily to hold the pH around 6.4. I am living in hope I have them sorted and can keep them (80+ still) alive long enough to be large enough to be a meal. They are a nice looking fish and growing faster the SP. Someone out there must have had good success with MC and be able to give us some good advice?

I've had a couple more losses but again only in singles space apart by about a week or so.
Still feeding but I do not feed every day so i'm guessing they are hungry when they are being fed.

Mine have been eating a small handful of pellets a day since I took the shadecloth off the big hoophouse that shades the greenhouse at this time of year. Since then the greenhouse system has been getting up to 17-20C so I feed in the evening when it is warmest.
One I put in an aquarium inside as he was the bullied runt, has really grown, and I think he may have thinned out the kribensis I had in there

I went and got another 50 Murray Cod a few weeks ago, and at the moment they are living in the DWC trough so that should be getting warm for them..

The system is running fine and hopefully is sitting at about 7.4pH at until the Shell grit in the Gb has been dissolved..

Juergen

Just wondering if anyone had any info to update regarding the temps for murray cod
Is anyone growing them in the cold mountain areas of victoria or NSW and how do they handle the cold weather

Cheers

In my opinion ideal water temps are similar to what is prefered by SP however I have not experienced the same excessive losses that I experienced with the SP, water temps above 18deg are best for feeding.