I know this is probably a stupid question, but can they be sexed in any other way than witnessing a male croaking. I know that with some mantella species you can sex them by seeing the sperm ducts in males on the underside of their bellies. Is this possible to do with a black PA frog such as D.auratus? Reason is because I am going to be bringing home 4 of these little guys( first time owning Dendrobatids, but I have had mantellas) in about a week with the intent of eventually breeding, so I wouldn't want to buy the frogs and find out later that they are all the same sex. Any replies are appreciatted!