Gerbils are okay for a BP but they tend to get "hooked" on them after having them for a while and it will be hard to switch them back onto move if you ever can't find gerbils or something. I would go for mice as well, but just on a side note: pink mice are far too small for a BP, even a hatching, though I think they would be ok for a chondro baby ( I'm not a big chondro expert)