Send one to me lol that will solve the issue... No but really usually fish that school do better in larger groups not paired groups they may both be males and might be having a territorial dispute or something to that nature. If you get more it will most likely lower the aggression.
What type of payara's are they? That's and armies tend to become territorial and extremely aggressive towards eachother where 1 usually ends up killing the other. Some have had luck with multiple armatus, including myself, but most I hear end up killing eachother. I've never heard of anyone keeping 2 or more tats together peacefully. If they're scombs, you would need a large group. I had 3 together and they were constantly slashing eachother up