You could look into Exodons, they're one of the most exciting fish to feed in large schools.
I've also heard they can be very protective of themselves. I read online somewhere someone once found one of their exodons had jumped out and he must have discovered it within a few minutes of its escape as it was still alive. When he put it back the more aggressive larger fish became aware it was struggling and started nosying around for a quick snack. The school of exodons quickly swarmed the weakened exodon and fended off the bigger predators.