What is bad about having different kind of snake live with your ball python?

All snake subspecies should be housed individually. Snakes that are housed together can spread mites, bacteria and diseases back and forth. The worst pairing is a python and a boa, because of a disease called IBD (Inclusion Body Disease).

If you keep multiple snakes of the same sub species together you should separate them at feeding time. If two snakes go after the same food item it is possible for one of the snakes to unknowingly swallow the other snake. This has happened at many pet stores.