Backyard Aquaponics
A place to discuss aquaponics

My silver perch have fed much better this winter. Is this usual once they get bigger? This will be their third summer.

Makes it easy to keep the veg going well when the silvers start feeding well whilst the trout are still in the system.

Interesting. Hopefully someone can confirm.

Hi Brian, maybe they think they're trout !

Could someone advise on the temp range for silvers?

Thanks, Pete.

Silver perch have a temperature tolerance range of 2 to 38°C with optimum growth occurring between 23 and 28°C. During winter when water temperatures are lower, silver perch will require less food and have a slower growth rate. At temperatures below 10°C the fish may enter a state of torpor, with greatly reduced appetite and activity. As the water temperature increases in spring and summer, the fish will require a larger quantity of food due to the increase in their metabolic rate.

http://www.dpi.nsw.gov.au/fishing/aquac ... emperature

Over winter here they basically eat very little and consequently grow very little.

It's worth noting that below 16ºC they have a massively higher risk of developing disease and/or fungus problems, especially if the temperature is fluctuating a lot.

I will have to look at the water temps, not sure what they are now. The past month or so they have been feeding quite vigorously feeding floating pellets out of a 2 meter deep tank even in the middle of the day. Chopping the water much like the trout. I am feeding them several feeds a day and they are lapping it up.

It may be just they have become more bold. Previously they have been very timid to feed with very clear water even in summer during the middle of the day.

Thanks Brian,

can you tell us how long it takes to get silvers from fingerlings to dinner plate size?
Will their growth be steady if their water was temp was maintained above 23 deg once the cooler weather sets in?
Do silver and jade perch have the same water temp issues?

Thanks, Pete.

No idea Pete. I am 8 months in to my first lot.

Yeah, they will keep feeding if you can keep the water warm, but that would require a crap load of energy. Not really an option for me or you looking at your location.

Dunno about Jade, I think they are a lot less cold tolerant.

http://www.seqfish.com.au/aquaponics_17.html

Jades need 18-32ºC, stop digesting food at 16ºC and start dying under 14ºC; under 22ºC they have the same issues with vulnerability to bacterial and fungal diseases that silvers have under 16ºC. Not a fish I can try to raise, given that my water temperatures over winter would kill the poor things quick smart and I'm looking at getting a solar pool heater just to keep silvers happy!

I have silvers and jades in the same tank. Have found that the bigger fish cope better with colder temperatures too.

My jade perch (about 600 g) look fat and happy having just come through a winter with water around the low teens much of the time... but not eating much... if at all. The SP ate pellets without much enthusiasm... but they never went off their vegies... leafy greens particularly.

I've lost no perch to disease... perhaps blind luck... or maybe because water is salted and good aeration

Main reason for post is to say that, even with their virtual fasting through winter if unheated, jades catch up and overtake the silvers in summer! If you want to get your fish to plate size quickly and are far enough north or can steal your neighbour's electricity, jade perch are the go.

Salt and aeration and general good water quality is probably the main reason (with luck helping out a little)! That's something that repeats itself in both my own fishkeeping history and with everyone I know who keeps fish, of whatever type - if your water quality and oxygenation are good, fish can tough out a lot of less-than-optimal things. If your water quality and/or oxygenation fail, all of a sudden things start going wrong.

(That's not to say that if something goes wrong, your water or oxygen must be substandard - stuff does happen. It's just much easier for stuff to happen if your baseline conditions aren't the best.)

Water is 16.5C today. It was 11C that I saw mabee even went lower earlier in the year and yes Dave they certainly ate green all year.

I have not salted my water, but not lost any SP from the fingerlings that first went in.

It seems jades are too risky, silvers slightly above border line and trout most probable with some water chilling techniques on hot periods for my area.

Pete.

Definitely true!! The silvers here at Cheidys Aquaponics Shop(formally Backyard Aquaponics) in Jandakot ( another shameless plug )have been smashing the feed for the last two winters. The growbeds are doing better than the ones with trout in them. We have about 15 Silvers feeding 3 growbeds in a 2000lt tank. Age of silvers are about 5 years with a very large and very happy 10 year old Moby Dick. One of Joels originals!! The silvers in this tank eat every day and several times a day.

Originally I had the idea to carry over some trout to try keep nutrients into the system at that cross over period spring and Autumn.

Seems i was backing the wrong dog.... Need to carry over some big perch from year to year.