If you want to add a GT or another fish to shift the balance go for it. I would make sure to change the structure around in the tank and even add some more so there are plenty of spots for the fish. Make sure the pike has some pvc or a tube it can go in to. Put the rock or cave that the salxfm is using to lay eggs on one end of the tank. Aggression will probably still remain with the salxfm trying to breed though. Maybe drop the temp in the tank closer to 70 if you have it up closer to 80.

