I have an EBJD in a 75, so more is definitely better. I get what you are thinking, but the 55 would allow more room to roam. EBJD's are smaller than the normal strain, but still 8 inches or so. I'd suggest 55 as the minimum. That extra 15 gallons is a big deal. Beautiful fish. Mine acts like every other jack I've owned, a log at the bottom until feeding time, then he uses every one of those 48 inches.