From all I've read about anthias (and I read alot) they're not known to jump but they eat a lot. To keep them healthy and thriving, you HAVE to feed them a variety of foods 2-3x a day. As 192clark said, if one is sick and weak the rest may not make it. BUT if you can get one eat in the beginning the rest will also join in. Don't let the scare you, the common aquarium anthias are fairly hardy (bartletts, dispar, lyretail, fancy bass to name a few).
I'll be keeping some in my upgrade they're awesome looking fish.
Good luck.