I was told I had male and female...They had 4 in the tank 2 larger 2 smaller. I asked if they knew male from female and they said it was 2 pairs in there. The 2 larger males and the smaller females. Does that sound right? Is there a way to tell for sure without venting? Just went and looked and the male also has a little black on the top of his head along with the lips and after looking at them yes they do always have black/grey lips. The close up of the one looking at you is the female. Sorry about your guy.