Nics are savage. Pound for pound one of the more capable fish I have owned. They seem to want to fight to the death. When they are in an active tank, they can not be the most aggressive fish in the tank. They will bully, non stop! Nics go good with Dovii, and Red Devils. Give them a nice hiding spot to go into to break their line of sight. That seems to be the only thing that has worked. They like to be at the bottom, so keep that in mind.