I gotta agree with some of the earlier posts. While it is sad, particularly for the Jag, it should not shock you. RDs are one of those fish that, once it reaches a certain size, is better kept in a tank by itself. You'll have fewer torn fins and the RD will look better for that. While community tanks of aggressive fish may work for some for a while, it is not fair to the "milder" fish to throw them in with bullies.