Backyard Aquaponics
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Hi. Where I live in KZN, South Africa we have large temp differences in summer and winter. In summer the temps during day are in 20s, 30s and some up to 40c. At night it goes down to the low 20s to high teens. Then in winter during the day it's in the mid to low 20s and the teens with some days down to 10c. And at night often down to single digits. What fish would be ideal for where I live? Thanks in advance for all advice.

Sounds a bit too warm for trout and a bit too cool for tilapia. Catfish might work, they are a warm water fish so you won't be giving them much feed when it's cold but you probably won't be growing much in the colder months anyway. Depending on how long the warm or cold seasons are you might be able to figure a way to switch between trout and tilapia (like bringing some tilapia fry inside to over winter them as a starter for next summer and buying larger trout from a hatchery so they won't take as long to get full size).

Another option would be to grow ornamental fish for sale, like koi.

There are probably some native fish that would work as well but I'm not familiar with what you have there.

Cheers

Thanks. I'll look into that. How difficult would it be to solar heat the water for Tilapia in the cold months? I've heard it works well. What do you think?

You could probably grow tilapia if you had the system in a greenhouse and were willing to heat the water if needed but it gets costly. The grow beds act like heat exchangers so if it's cold out, a lot of heat will be lost from the grow beds. If you aren't planning on growing many plants in the winter you could setup your fish tank as a Recirculation Aquaculture System with it's own solids and biofilter. This type of setup would be easier to retain heat in since you could put the RAS in a heated building area. During the growing season when the temps are high enough for Tilapia, you would reconnect your grow beds and use the RAS nutrients for the plants.

Tilapia start dying at around 12 C but they like water 20 - 21 C and above up to around 32 C.

I'm in RSA Johannesburg.

Current afternoon temps is 30° and my water is 22°C at bed time and 17° in the morning.

I have 2 x 15cm Tilapia rendalli and 10 Mozambique Tilapia (Blue Kurper). The Mozambique has a wider temp range. 10° - 38°C

Planning to do trout next winter. I only finished my built in August and the coldest my tank got was 9° if I remember correctly.

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My IBC System

Thanks guys for the advice. I'll do some research into it and what others use is SA.

The Temps are similar to Sydney so you should be able to raise a good crop of trout over winter.If you get good size fingerlings in autumn as soon as the water temps are below 20c, and you don't overstock the system so you can feed them to the max then you will get plate size and over by summer. Good luck !

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I'm a big fan of tilapia for a lot of reasons that I won't go into, but I would get an insulated tank and put a heater or two in it to keep the water warm in the winter. In the summer it shouldn't be a problem.

Does the system suffer from changing from one fish species to another? Do I need permits for rendalli in KZN?

The blue tilapia in Hong Kong,live in some ponds out side 30 in the summer down to 10 or less in winters which mybe only two to three months survive..

There is some variation among the different Tilapia and even within each species. They adapt up to a point at least.

Oh okay. I didn't know that.