It is almost impossible to tell the sex of FBTs. I thought I had 2 females and a male, as two are morphologically female as they are larger and to me look very frog-like (the shape of wild frogs up here in SK). My male is smaller and has a rounded body (width not girth). He also has some extra skin on his neck (expands during vocalization). The tricky part is that I have seen all 3 calling. Females are not supposed to call but I have heard of many accounts of females tricking their keepers into thinking they are male (eggs laid in a male-only tank). My answer is: does is really matter which sex they are? I've given up on figuring out mine unless i find eggs.