There really is. I asked the girl at the fish store for a couple of males, since I believe the first two are female. She turned around and looked at me, and said "I didn't think there was a way to tell." I said "There is, but I'm not very good at it." I looked at them all night, but they were too active to figure out if I truly do have a male or not. I think based on the top view in the bucket that I might have ONE out of the six. It doesn't look like I will be very successful breeding them for a while! I read somewhere that the ratio you want for breeding is 2m:1f. Oh well. I guess I'll just have to pony up the bucks for more pandas in the future!