castaway in answer to your question i have silver perch 80mm to 100mm.i have also included some photos of my system.I have used pea gravel instead of expanded clay, yes i know tight mongrel.but still learning.I have been looking at your growth rates,blows me away
I don't think it makes the slightest bit of difference what gravel you use. You have a neat looking system. In relation to your earlier posts about spindly growth, I'm wondering if your system is getting enough sunlight as 80 Silver Perch must be pumping out a fair amount of Nitrates but your readings were pretty low and the plant growth looks fairly lack-lustre. Are the fish being well fed and eating a lot? I'd check to see that water is getting to your plant roots and there's no odd blockages as your other grow bed with a silver beets looks great.
As to been blocked the answer is no,feeding is not great, i feed them a tablespoon to each tank at somewhere between 2 and 6 pm.They don't seem to eat all the food and there growth is not great.the food i got from a fish farmer who in turn got it from tassie.he uses it with no problems that i know of.
Are the fish sprightly when you put your hand into the tank and zip around in a lively manner? Or sluggish and just like to mope around not moving much? Maybe not enough dissolved oxygen or water temperature too cold? Check the water temperature and crank up the oxygen going into the tank. You are using an aerator to air stones as well as the main water pump splashing water back into the Fish Tank 24/7 or on timer?
DPI Silver Perch recommendations are: Temperature tolerance ranges from 2°C to 35°C. Optimum growth rates occur between 20°C to 30°C and growth is negligible below 12°C.
I know the Jade Perch I got are still eating strongly. Water temp is 23 degrees. They are very sprightly and zip around with plenty of energy occasionally bashing into the sides of the tank with a thump which all points to healthy fish. I also feed them picked greens from the growbeds above them which they love to eat. Try varying your fish diet as well.
My water temps are down to 14.7 this morning. Fish all off their food. It is amazing how much the water temp affects their behavior.
I really don't want to electrically heat the tanks this winter. Power costs here in SEQ have gone up close to 30% since the Gov did us all a favor and privatised the system.
14.7?!! Gosh Murray! Thats Cold for SE QLD. I'm right on the coast so the temps are more stable and warmer. Still - I would have guessed you'd only be down to around 18 - 20 degrees. You probably get a frost at your place in Winter? I've been rolling a rubber mat over the fish tank hatch at night as we've had a few cool nights - but forgot last night but I dont think it makes any difference. Sun on the clay beads during the day warms up the system a bit. Only need a strong cold offshore wind to drop the temperature quickly.My water temps are down to 14.7 this morning.
I wonder what the temps are in Perth?
I've just checked my water temp,and it's 21c,at 11.33pm.The average temp max is 27.7. The min is 13.7 in this month of April 09.Something i forgot to mentioned is the fish food i brought was 5mm, i crushed it down to fine flakes,is this to small.Have also been thinking since my nitrate level is down would it hurt if i dropped say, one teaspoon a day of urea into the system, to bring the nitrogin levels up.And If so would this also sustain plant growth through winter
Hi,
I wouldn't use urea in a system that already has fish in it. Try Seasol instead.
Gary
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Castaway when you say vary the diet what do you suggest
Silver perch are omnivores consuming zooplankton, small crustaceans, aquatic insects, molluscs, algae and plant material.
There's probably nothing wrong with the pellets you've been feeding them but try offering them a variety of different feed and watch and see if they show any interest. A lettuce leaf for example. Strong water temperature swings of a few degrees can also play a part in putting them off their food. Add a screw cap lid full of Seasol concentrate directly into the water tank every morning to keep the plants growing, adding vital trace elements that they need.
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