The male is incredibly loud! He started off quiet but once i got the bigger tank and he had more water, he got so loud you can hear him downstairs across the house. The other two never make noise. My male-Hippity- is also thinner then the females, no matter how much he eats. My two females- Hoppity and Fatty- look smaller with round bellies- Not large from the underside, but more like round middles. I've read mixed things on sexing FBT, so my babies build might just be coincidence, but if they call constantly, not just when being attacked, they are males.