Lol, white clouds are just too brave for their own good I've got some in with one of my bettas, though no where near the threat, they've gotten pretty darn close to his mouth. They steal his pellets, and the poor boy just looks around, dumbfounded, like "where'd my pellet go?"
When I first put them in there with him he chased them and they would school and it confused him. Now he doesn't bother trying to catch them. I'm not sure if the prawn tail keeps his teeth trimmed but I can hear him crunching away on it so I hope it is helping.