This is a bit on the semantic side of things, but since (imho) we should strive to understand the fish we put in our tanks, I think it is relatively important to understand the difference between schooling and shoaling.
Schooling denotes a group of fish swimming together in the same direction in a coordinated manner, often to confuse or intimidate predators. Unless you have a 10,000+ gallon tank with large groups of predators and prey-fish, you'll never see true "schooling" behavior in home aquaria.
A shoal of fish, however, is a group of fish that hang out together for social reasons, but are acting independently of one another. One may break off to nibble live rock. One may be swimming the other direction. One may be chasing a shoal-mate. This kind of behavior definitely does occur in home aquaria - particularly in larger tanks where we can house multiple specimens of the same species.
Since I'm new to keeping fish in home aquaria, it's hard for me to speculate as to the fish that have the greatest propensity to shoal...however, with about 2,200 hours spent scuba diving, occasionally as a member of research teams, it is my opinion that no reef fish in the wild shoal as prettily or as interestingly as anthias.
Just my $0.02....
