I have 8 BGJD's that i have been raising for 4 months (when I bought hem they were about 1 inch) and about half are nearly twice as big, as the others, around 3 inches or more while the smaller is barely over 2. I'm thinking the smaller would be females. I'm going to give a friend of mine 1 male and 1 female and I wont to make sure that is what he gets. I'll post pics later. thanks for info.