Hi Alex. Gender can be tough when they are very young. Males will also grasp other males like this in dominance so it's possible they are not breeding but establishing who's the boss! Sexual maturity is generally around 9 months of age but I've seen my 5 month old chase my girls around. Females tend to be larger than males but this is also not a guarantee. Look just behind the front legs of your frogs. Males have a gland...sort of looks like a pimple...directly behind their "armpits". Females will also have a longer "tail". Have you heard them singing yet? My boys sing when seeking a mate but will also chirp at one another prior to what I can only call awkward chest bumping. I have never heard the females sing in my tank. I don't believe they do but I could be wrong. Easiest identifier is the glands under the arms. They are not visible though until they are a few months old. I hope this helps.
