I have a Blue Faced Duboisi and I added a Green Severum today along with a Gold Severum and the Deboisi keeps jaw locking with the Green Severum. Is Thier any way to prevent this behavior?

The only way I know is to separate them I had this problem with one of my cichlids and he killed one of my other fish so watch them close if it gits worse move him. I sold my fish when I reinterduced him he attacked all my fish. Stress is bad on fish.