Another vote for blue eyed/long spine cardinals. They group really well.
Another excellent species for a group, although they won't tightly shoal, is allens damsels. They bicker a little amongst themselves but don't cause any issues. They really make a great addition.
Another excellent species for a group, although they won't tightly shoal, is allens damsels. They bicker a little amongst themselves but don't cause any issues. They really make a great addition.