Fire belly toads

my toads mate a lot, one of my toads that I named swimmy never makes the mating noise and is pretty slender and is not as wartier as my other toads. I think swimmy is a female but for one reason I am doubtfull, when the other toads make the noise and...

grab onto swimmy she/he makes the dismount call.
so my question is how do I know the diference between male and femail fire bellied toads

Female fire belly toads are usually bigger with longer legs the only real way to tell if their female or male is by the noise they make when their mating if the toad is always on the other toads back then it should be a male, it might just be that it's too young and not mature enough. Sometimes a male fire belly toad will mount on another male.