My severum was being a bully to my oscars. So I put a barrier up. I partially removed the barrier once they were of similar size So there’s basically a wall with an entrance but now he won’t leave. Just wants to stay in his area. How do I fix this without serious fights like before?
He may just have claimed the one area/side of the aquarium. When I kept African cichlids, the only way to “reset” territory was to rescape the tank (and even then they would hash it out again for a bit) or to overstock the tank, in my experience.
You succeeded in stopping the bully problem. You just have a kid that won't leave the room. I would leave it be and let the severum and Oscar figure it out. Or you can change the entire landscape but that might open doors to aggression.