Backyard Aquaponics
A place to discuss aquaponics

I have spoken to the local barra farm, they said I can get some fingerlings in oct/nov

what would be the minimum GB/Water required for 20 of the suckers?

700 - 1000L .... with a minimum growbed capacity of at least the same...

And a heater to keep the water above 20 degrees...

right now, in mornings I am at 14.5c and evenings 16.5 - this is only with 160L FT and 60l of GB

(concept system - 14 small comets in there)

I reckon, buy the biggest fish tank you can fish tank you can possibly afford. - You won't regret it.
Preferably match this volume with grow beds.
Then work out many fish you can fit in it!

Growing Barra in our Adelaide climate is possible, but challenging...
Buy the fingerlings as advanced as possible when the weather warms up and be prepared to provide supplementary heating if need be.

I grew them last summer and found it lots of fun. (Mind you, I did harvest some smallish fish)
The lucky ones are now inside, in a heated aquarium.