Schooling fish behavior questions.

I had about 15 white clouds in a 55 once. They didn't really school at all. They did reproduce like crazy though.

I personally believe that fish schooling in a 20g is sort of difficult. In larger tanks, maybe even a 29g, fish have more room to move through the tank and get away from each other and likely stay closer because of that. In a 20g, maybe less in a 20 long, fish can move from one end of the other without losing sight of each other and stay loser. Just my observations of some fish.

The schooling is definitely more noticeable in tanks like 75+.

One needs to remember that schooling behavior is a defensive mechanism, often to avoid predation. To encourage schooling behavior, the fish need to experience a threat stimuli. Having a predator in the tank will do this, or shadows moving from overhead.