My dad had a big bala until it jumped out of the tank even with the hood on. Weight down your covers people if you want to keep them and other big fish. He grew pretty fast on shrimp mostly. to about 10-12 inches long and pretty high bodied.
Tin foils grow FAST. Mine went from 2.5" to 8" in a year. They are currently around the 10-11" mark. Balas grow SLOW. Iv had mine for 14 months and they have grown 2-3" max.