Backyard Aquaponics
A place to discuss aquaponics

This is interesting as from November to March/April our outside water tank gets well below 10 degreesC and this last winter there has been a thin film of ice on the surface in the morning. I have goldfish and grass carp in there and although they appear sluggish they respond to a stick being placed in the water and gently moved about. ( My missus says I'm the same - thats another story). However we kept water cress,winter lettuce and peppermint growing in the NFT (sort of) system all the the way through the cold spell and now have the water cress,chervil,parsley and conical cabbages in there. We are hoping to build a system in a building so that it will easier to control the temperature and when we get it going we will set up a thread to show the progress.Fingers crossed.

no good for trout there wd?

Hi Creative. To get the trout fingerlings I would have to post a minimum order of 100.000 which is way beyond my pocket. When we get set up we will be using common carp fingerlings which cost about 35p each with a minimum order of £200 delivered. (Don't ask me to do the conversion into Aussie dollars.)This seems pretty good. We will be able to see them through the winter inside without having to pay excessive electricity bills. It should be very exciting.

Hey WD.... maybe contact this member.... might be able to get you some small numbers of trout... mind you, still a distance between Wales and Scotland.....

http://backyardaquaponics.com/forum/vie ... ght=#19171

He's involved with work with the University of Sterling

Thanks Rupert,
I have sent him a p.m whether he is still at the Uni I don't know as guys move about a bit and sometimes they are out in the field.
Do you know of anyone who has successfully raised trout in an aqua. system in colder climates?

I had a look at the trout fact sheet on one of the government fisheries websites, and it seemed to be saying that they are a "cool water" species, needing temperatures between 4 and 19C, with optimal growth between 7 and 17C.

If you're getting ice on the top of your tank, is the water temp less than 4 degrees? Having recently lost a LOT of fish apparently due to cold water, I'd urge caution. If the carp are happy, stick with them.

By the way, can/do you eat them? In Australia the thing we call European Carp (one of our many introduced species) is not considered a good eating fish - in fact I'm not sure if it's considered edible at all?

Jimmy, trout should survive 4 degrees ok and a bit of ice on the surface wont bother them. Many of the lakes in Tasmania (and I imagine places like Scotland and Canada) freeze over in the winter and the trout are all still there once the ice thaws out.
As for the Carp they are considered a great fish to eat in many Asian countries but here in Aust most of them end up as liquid fertilizer. The problem with eating them is that they have heaps of bones!!

Fair enough!!! Goldfish are essentially carp, aren't they?

yep goldfish are members of the carp family

Basically, tough little buggers they are too.

I have seen my Tandans down to 4.7 degrees and they were looking a little sad. I have since added a heater on a timer to keep the temps up a bit and they are looking happy. The goldfish at the same temperature (4) were fine.

Nova

I think it would add to the experience if you had to cut a hole in the ice to harvest your fish. The ice on top acts as an insulation so the water may be 4 degrees or more underneath.

You may not have to feed them often at these temperatures.

My 10 or so goldfish are doing well in Hahndorf (in the Adelaide Hills), growing fairly well. They're just in an aquarium on the ground outside and it's been FREEZING here. I mean, frosts came through and wiped out our potatoes and even damaged the lawn, so it's been pretty darn cold. But the goldfish seem happy as. I also put in a couple of things called "Australian rainbows", whatever they are. Haven't seen them of late but as they're not floating on the top I'm hopeful...

Moving house soon, so will hope to scale up the system considerably!

I dont know about aquaponics,I just typed out a reply pressed the wrong button and the bloody thing disappeared.
However I think I will follow jimmy-d's advice and go with common and grass carp in the first instance as they are pretty easy to get hold of here. There is a good market for carp with the Asian and slav markets. The Czechs make a big deal about carp at Christmas time so that is one avenue to explore. Also we do not restrict ourselves to the fresh trade as we have a local smokery and a sea salt processing company here on the island so smoked carp and salted carp are a possibility. As for eating carp they are delicious if cooked with herbs although I found them a bit boney but so are sea bream and they are delicious as well.
One last point on cold fish- what about freshwater eels. I am told that no one has successfully bred eels in captivity but I stand to be corrected,but there are a lot of commercial undertakings in Europe looking at eel farming .Keep the advice coming.

don't eels go out to sea to breed, i believe much of their breeding habits is as yet unknown!

on the water temp, i think thec is the golden number as water has this quirky property where its density is lowest at 4C hence why ice and also cooler water can be located HIGHER.

Not trying to be pedantic, but I think you mean water's density is HIGHEST at 4 degrees. Below 4 degrees (e.g. ice), it is lighter, and above 4 degrees it is also lighter. From memory the relationship is approximately a sixth-order polynomial :-)