I started with 2F/1M in a 125 Gallon. Within two days the male was dead - tail was bitten badly. I then added another female slightly larger than the other two. She was dead in 2 days as well! The area just behind her Pectoral fin was bitten very badly. The only other fish in the tank is a 1.5 Royal Gramma. For some reason the female that came with the suspected killer has not been touched. I think I know which is the killer because she seems the boss of things. So I'm thinking I have a vicious killa female in their. Is this posible? and if so, will adding four more fish change the outcome? Or, will this female continue to kill?