unsure, started developing red sores on body, so I started treating with melafix and didn't last through the first night. really enjoyed these guys, the larger one was close to 6" , the other one was a little smaller at 5 1/2". friends that didn't know a thing about fish thought they were pirahnas and that they looked really cool. hate to see them go because i got them when they were tiny. oh well time to move on . thanks guys.