Hi Helen,
EBJDs tend to be more docile than the regular color phase, so they will need to be at least an inch or so larger than your regulars. If there's going to be any bullying going on you want it to be the Expensive one doing the bullying.

Also, EBJDs tend to be rather fragile until they reach about 3+". I started out with four from very good stock, fed lots of live and frozen foods, and have a
UV Sterilizer on their tank; and I still lost two. If you can find a 3"+ EBJD, its well worth the extra cost. They are great fish with lots of personality.
Mark