Green Chromis questions

[Dorkel Marine 1]

Is there any record of a successful chromis school. The way its sounding here all there good for is cycling a tank. Which I of course don't agree with. However, I tried 3 in a 30 gal. One became dominant and eventually the other two died and then the big one must of died of lonliness or something.
They're a beautiful fish when the sun hits them and they're schooling. That's why I was wondering if anyone has had a successful school in a larger tank maybe.

George Muller