Generally speaking, yes. As long as your tank is big enough and there are enough places to hide, they will likely just claim territories and chase each other with little or no injury. The only time you might have problems is if they spawn, but I'm not too sure as I have never tried this myself. How big is your tank, and how long has it been set up? Apistos are a lot like rams in that they are very picky about water quality and do not fare well in newer tanks. What species are you considering, apisto cacatuoides?