FBT's do tollerate each other, but they don't need to be kept in groups. Carlos already gave you the tips you need, and he is right about the pebbles. FBT's can be monsters when they are eating. They are not the best hunters in the world, and they attack their prey in a rather clumsy way. It's possible that they don't grab the prey but someting else, and if it will fit in their mouths, they will swallow it. I once saw one of my FBT's attacking a fruitfly, and he ended up with a mouthfull of moose. He just sat there, trying to get rid of the moose. He almost looked ashamed of what he had done. LOL!