The easiest way to tell a male and female fire-bellied toad apart is to observe them. Males will call to the females by barking like a puppy. Then they will hop unto the female and hug it around the waist. Sometimes they make a mistake and hop unto another male. If that happens the other male toad will let him know he made a big mistake. Only males bark so if your toad barks it is definitely a male. But just because your toad does not bark does not mean it is a female. It may not bark because there is no female around to bark for. There is no easy way to just look at a fire-bellied toad and tell which sex it is.