My guys went threw this phase.. and imo as long as its just the fins getting shredded abit.. I'de leave them together ( since you already pulled him let him heal-up and de-traumatize, then try again) My cats had to figure out who was "top dog" good chance one or the other made that bid and the other one "called him out" If its just abit of fin shredding ect its not seriouse aggression... if the one is constantly chasing/aggressing then its def a pull situation. Just like other fish they develop a pecking order, the hard part is figuring out when it's "safe" to let them slap each other around abit and when serious intent is being made.
When you try again move any décor around like you would w/ cichlids... maybe take the hybrid out for a measure? that lil' bit of stress might make the initial intros go smoother. Otherwise a good feeding of the hybrid the day before might help as well if hes being the aggressor. otherwise making sure to feed the fish good that night. when my guys go a few extra days sometimes they will squabble abit.. imo its getting out "hunger aggression".
