It'd probably grow to it's typical wild size... see fishbase for max/average TL sizes of cichla species... JohnPTC has some of the largest cichla I've ever seen in his monster 10k g tank.
My cichla tem are huge already. around 24". I have 3 of them and 2-3 are 18" i think. It started in 800gallon tank. now move to 2800gallon. So i wonder if they will still grow.