Backyard Aquaponics

More Fish
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Author:  Pips [ May 24th, '20, 11:50 ]
Post subject:  More Fish

Hi There,

I have a few questions I would like help with.
I have a 250L tank with 5 Jade Perch in, and they are about 100mm long and one is about 60mm long. I acknowledge its a small tank, but could you put more fish in there to make up for how small they are as I am not getting much nitrate for the plants. I was thinking the next project will be to go to an IBC tank and use the 250L as a buffer tank, so im hoping to have a lager tank to move them to in the next few month.

How do smaller fish go being added to a tank with bigger fish?

I have built a heater for the tank which is basically a temperature controlled 2200W heating element in a buffer tank that the bell syphon goes into with a pipe into the tank and the water heats slowly each cycle then runs it into the fish tank. I have currently got it set at 23deg C. Does anyone have any ideas if this would be a good temperature for Jade Perch during winter? Im in Brisbane and the tank got down to 12deg C the other day :(

Excuse the mess of the cable as Im cleaning them up now and about to insulate the heater tank too.



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Author:  Dangerous Dave [ May 25th, '20, 19:34 ]
Post subject:  Re: More Fish

Hi Chris

I have Jade perch too.

Your fish will love it if you heat your water to that temp. But electricity might be expensive... My experience was that it takes a lot of energy to keep water warm in a recirculating system, even with insulation.

I'm not too far south of you in the Northern Rivers of NSW. It gets a bit cooler here than Brisbane. I was worried about the JP in winter at first. But I've had a number of batches through winter in recent years, without heating. Haven't lost a single fish. They stop eating on really cold days, but even in mid winter, they'll have a good feed on a mild day.

I can't speak from experience about having fish in the same tank of very different sizes. I don't think it will be a problem with jade perch but someone else will hopefully be able to give better advice.

it's hard to give advice about stocking rates without knowing more about your grow beds. In particular, wet media volume. The rule of thumb is that you can have one fish that you intend to eventually grow to eating size (plate size) for every 20 to 30 L of wet media.

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Author:  markg [ May 28th, '20, 08:58 ]
Post subject:  Re: More Fish

Hi Chris

I've had JP and SP in Bris (Bayside) in an IBC FT with no issue.

I did however decide to:
1) wrap the IBC in bubble wrap;
2) turn off the pump for a few hours using a timer at night when the temps' dropped right down. For myself at least, I had it off at 12am and on at 8am but your circumstances will be different WRT volume and stocking levels. This reduced the heat loss from the FT. (The fish really drop their metabolism as the temps falls so ammonia and DO are much less of an issue.)

Increasing water volume of the FT will certainly moderate temp fluctuations...both in winter and summer.



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