Introducing me!

[John]

perhaps I should just build on this and get them more used to people?

Well the key is to get them to associate you with food, so persistent hand feeding should hopefully pay off, although like I said, some anurans never tame down.

I wondered if the difference in body shape might show a difference in gender? I've never heard them call.

In most anurans the males are either slightly smaller or much smaller than females; they tend to eat less than females and it's hard to get them to put on weight (so they always look skinny in comparison). In Kassinas, both sexes are usually the same size so this leaves you with the latter method. As for calling, some Kassinas only call from in or near water - I don't know if this is the case with your species but it might explain why you haven't heard anything.