I had a single anthias for sometime. It did not do well. One thing to consider with anthias is your ability to feed multiple times a day (3+). They have very high metabolism and need to eat small portions several times a day. This can also be difficult if you have other agressive eaters in the tank as my anthias was not. I think this was my downfall as I am gone during the day.
I have also heard small schools do best 1 male 2 females. Possibly someone with more experience with this particular species can offer more guidance.