^This.One thing you'll read a lot is that many fish that will in shoal in nature won't in a tank.

Atlantic Chalk Bass, beautiful and stay small.
one concern for Anthias is since they are hermaphrodite fish, the one that becomes the male will potentially always be aggressive to assert dominance in the group, this could result in killing off any females that may threaten his "rule" to the point you may only have him or him and one other female, not exactly a "school" unless you have a large enough tank.
My yellow tangs hang together all day. I have 6 chromis that stick close. Then they spread out......then group up.
I like chalk bass, but I would say that I had three in a tank, two stuck together fairly well, but the third was an outcast.If you have the space to add a bunch of them, you would probably have better results. There are also a few others that will stick together from the bass family (lantern bass, royal grammas).