So I have been doing a lot of reading here and have become very interested in EBJD. My question is how can you tell an BGJD from a normal? Do you need to know the source of the fish or do they have different traits from the normal? Thanks!
You can't tell, they look exactly like normal JD's. So you would have to know from the parents.

Yeah you can only tell from the parent fish. If you interested in EBJD or breeding them I suggest breeding your own BGJD.