They grow quickly, eat anything, and usually leave other fish pretty much alone, but they do love to play "chase" - which can stress other fish out. When they get bigger (6 inches and up) they will dig up the whole tank. I have a 75 gallon tank with a few gars, and my pink tilapia in it. He has excavated the whole tank, pushing all the gravel to each side of the tank. Very fun fish.