Apistos swim all over the tank. While they tend to stay lower, I've had no problems with fighting as long as water quality is good and they are well fed. Mine have never been territorial and I've kept the same ones as well as viejitas, and borellis. Adding females is always good. I keep 1 male to 2-3 females when possible (not all make the shipping sad to say). Even when my apistos paired up, their territory was small and I got them at a young age (they don't live long 9-3 years) so they were used to each other.