Well I didnt plan on the the second one until now. As the point I got the first I didnt know you could only have the male/female pair. Now, I am getting another from someone else and they are not sure either. I can put the second in another tank I have set up but would rather keep them together. I thought there might be a way a LFS would know a way to "look" at them and tell, like a goby with the dorsal fin.