However many you get, I suggest you get them as big as you can find. The smaller they are, the more chance you have of loss. And, if you put anything else in with it/them, I would wait until the EBJD is at least 3+" to increase the chance of survival.
I got 4 ebjd's about 1.5 years ago, they were around 1 inch when i got them. they had the 55 all to themselves for awhile, sadly 2 died within a month for no appearent reason. one died six months later. I was left with one beautiful fish. He is up to about 6 inches and thriving. i get nothing but compliments on him. and this one fish was well worth the price of all 4. i do wish they all survived though. I would go with the ebjd's for sure
Josh