Thursday, 12 March 2015

European Perch

I have been concerned for some time with the Perch. 
You may remember they were introduced to the system last November.
Following good practice with the introduction of new fish they were isolated from the main system. Their water was salted to 3PPT. They settled in well. Perch are tough fish. They will tolerate temperatures from 4*C to 31*C. This was my main reason for choosing them.
After two weeks I turned a couple of taps, switched off the dedicated pump, and they were connected to the main system.
Everything was fine. Perch are not aggressive feeders like Trout. I fed them sparingly.
I would occasionally  buy some ‘red worm’ from the local aquarium shop
Winter temperatures were cool and they were almost in hibernation.
Their tank is outside, well insulated and sheltered. When frost or ice was forecast I turned on the heaters to keep the FT temperature above 4*C. They seemed fine. But;
Really just marking time.
So now I am asking myself was November too early? Should I have waited until now? Feb/March?
Anyway. I decided yesterday to act.
I again isolated their tank. This is where the design allowing a tank to be isolated quickly and easily paid off. Turn two taps. Drop in the pump, push fit connector Happy days!
I also decide to heat. I am using a 300W aquarium heater set to minimum about 16*C
Change can stress fish. I added salt to their system to 1PPT. That is one part per thousand. Water tests were good: Both Am and Nitrite negligible. I am keeping the PH slightly high at 7.7. I think this aids bacteria in cool temperatures. I will adjust as things progress.
This morning when I checked them their were fine. Again this evening good. Some fish now not hugging the bottom. I added one teaspoon of trout food. Some feeding activity but slow.
There is not a lot of information about E Perch in AP. Evidence from Ireland suggests 23*C is the optimum temperature for commercial farming. Growth rates at 11*C are reduced by about 60% 
Now in my garden setting optimal growth rates are not my main objective.  Hardiness and ‘taste on the plate’ are my main deciding factors. 
I do believe that European Perch can and should be a major part of UK aquaponics.

Only by sharing knowledge and experience can we move on.

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