Depends on the fish, but jags will get BIG and most of them tend to be less tolerant to tankmates. It may or may not work but who knows. GreenTerra had a huge jag who lived semi peacefully with a huge RD, Persei (sp), Festae, Bocurtti (sp) all huge full grown male specimens. The Jag was the boss and lived with them all for his entire life. So anything can happen.
http://www.youtube.com/watch?v=KXD-99CNcp4&list=UU3FB_GUpuxxE5v8eIVKrgSg&index=3
http://www.youtube.com/watch?v=KXD-99CNcp4&list=UU3FB_GUpuxxE5v8eIVKrgSg&index=3