Backyard Aquaponics
A place to discuss aquaponics

http://www.livefish.com.au/tropicals/ci ... l-8cm.html

I was wondering if they are fast growing.

From what I understand they will eat vegetable matter as well as animal matter like Silvers.

I'm trying to find a viable alternative to tilapia for Queensland.

They are called red devils for a reason.
You will end up with one fish with them in a bare tank

So very true, once they are large enough to pair off, you will end up with exactly that... a pair. They are very aggressive and very territorial as are most cichlids from South / Central America and Africa.