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Murray

Murray Cod

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Hi all,

Algal blooms are all part of getting the system in balance. I am not concerned because I run air pumps to keep the DO level up. Problems usually occur on overcast days as the algae cannot produce enough oxygen and thermal layers in the water stop the exchange so the lower level of water can become oxygen completed. Then fish die. Additional air solves this problem.

My pumps pick up from the bottom of the tank ensuring I get a complete turnover of the water.

The algal bloom will slowly subside and their bodies will produce ammonia. The system will absorb this okay.

If all the algae died at once I would be doing a quick water change.

Regards

Jonty

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My Murray Cod are going fine.

I vacuumed out the tank again today using a piece of 20mm hose as a siphon.

They are real little sticky beaks, darting up to the end of the hose to take a look and sure enough one went up the hose.

It is a piece of that clear plastic and it had a kink in it about half way. The little Murray got stuck there, so I was able to shoot him back out again.

They congregate at one of the tank wherever it is darkest. I clean out the fingerling tank every second day.

I have the tank covered with a piece of plywood.

With 447 Murrays in a 250 ltr tank I have to make sure it is clean. The water supply is coming from the main tank via a bio filter then it spills out via an overflow into the main tank again. I have an air supply with two air stones, and the water enters via a venturi, so there is a good air supply as well as water that has just gone through a bio filter for cleanliness.

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Good point FF. The bio filter I use for this purpose is a commercially made one and has a UV light fitted as well as the normal bio filter action. The UV light is used to kill algae etc when necessary.

I use the bio filter in special circumstances where it can be moved easily onto a temporary tank or similar. In the case of the Murray Cod fingerlings, I want to make sure the water quality is good until they get established and I move them to a more permanent home...into their own tank and attached grow beds.

I will have to move them a few times. I have 447 (approx) of them, so as they grow I will have to set up a few 2000 ltr tanks to accommodate them properly, and to keep the stocking density to around 50 kg per 1 cubic mtr.

In theory, I will expect to have around 450 kg of Murray Cod in about 1 year, so they will need approx 9000 ltrs of fish tanks to live in.

450 kg of Murray Cod :D Can you imagine the BBQ.......:)

Actually, I am beginning to think I should be thinking of a larger grow trough system for them, or perhaps treat it as an aquaculture project and attach a swirl filter and particulate filter and all that kind of stuff.

Anyone got any advice or suggestions as to how I might go ahead ?????

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Hi FF,

So why use a bio filter when you can use a grow bet and get plants for nothing

A trickling bio-filter (as distinct from the pressure filter that Murray is referring to) is lighter so it can be moved at will, has a smaller footprint and (since it doesn't have plants) it can be used inside. It will operate with salty water and is cheaper to put together.

Both grow beds and trickling bio-filters provide for nitrification.....it's a matter of horses for courses.....we use both depending on the circumstances.

Gary

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Gary, have you ever made any measurements of the level of nitrates and ammonia coming out of your trickle bio filters.

I remember you saying in a thread somewhere that your trickle filters have a worm population in them.

How effective are the worms in dealing with the solid waste deposited in the bottom of your trickle filters ?

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I had one of those pressure filters when i cleaned it out to sell poo stink couldent get the smell off my hands for days [so will a fish tank run on only a bio filter] i am getting trout soon and want to put them in a semmy seperate system[a nother ibs with a viewing window with a filtering set up] [turn on or off 2 taps to connect to the larger system]

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Murray and Gary,

The colour of the fish is fantastic when the sunlight hits them. Greedy little blighters when it comes to feed time. My water is still a bit greenish so I drained the tank this morning to inspect my lot. There's about a dozen that are around 100mm and fat whilst some of the others are still quite small.

I am going to put another holding tank in tomorrow and will have to grade them or I might only end up with two fish - 1 about a kilo with a 500 gram one stuck in the mouth.

Regards

Jonty

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Hi Jonty,

They'll be even better looking in a few weeks when the black and white markings on their sides become more pronounced. In my view, Murray cod are one of the nicest looking freshwater fish around.

Gary

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Mine are not growing as well as Jonty's, but they are doing ok. Will have to move them soon to their own tank....a bit bigger than the 250 ltr I have them in now.

Yep, Martin...I can't wait till the day I can slap one on the barbie.:D

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Hi Martin,

You blokes are going soft! Beautiful colors and all? Think how good a couple of freshly smoked cod fillets will look!

Since I have to look at them for another six months or so before they get invited to lunch, I figure they might as well be nice-looking, too.

GaryD

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Was at Rays Outdoors picking up some tent pegs yesterday. They had too quite large aquariums inside, close to 1000lts I would say. One tank had only 2 fish, a 3kg murray stalking silently and a 200 gram jade perch stressed out of it's mind. Apparently there used to be a dozen or so fish in the tank, so the jade has managed to fly under the radar until now.

The other had 2 barra, easy 2 kilos each. I then noticed half a dozen fish around the kilo mark doing nothing on the bottom of that tank. Blow me down, they were sleepy cod, in Victoria! I commented to one of the staff they must be running around 27C water temp. He asked me how I knew and we have a new AP convert! Gee they were just right for the plate. The barra looked very very sad tho, need more room or to go to the tummy gods.

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Sleepy Cod in Melb......Very interesting TT. Just goes to show, anything is possible.

And as amazing as may be to we AP's the great majority of the public have never heard of Aquaponics. There is a long way to go.

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Hi all,

Moved 53 murray's into their new home. Most were around the 100 mm mark and were at least a third bigger than the remaining ones. These fish certainly like their tucker. I am using Grobest Barramundi. So far no dead bodies.

Gary, the colours are fantastic on these fish when they are actually netted and can be seen up close. Was intending to take some photos. Unfortunately my wife was out shopping and I had my work cut out doing the move. I had the camera with me but had a senior's moment. Oh well!:o

Regards

Jonty

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What size tank have you put them into Jonty.

How many ltrs is the tank.

I am feeding my Murray's is on barramundi feed also, but mine are not as big as yours Jonty.

give us a few clues, what you are doing get the fish growing so well.

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