Lynn Has given you some great options. Tincs are great in groups until they hit sexual maturity then you need to put them in pairs to keep the aggression down. You can go 1 female and 2 males in the group, but will need to watch and make sure one male isn't constantly being bullied. However up until sexual maturity you could house a decent group in there as long as you separated them all around the 1 year mark.

There are great group frogs such as the Auratus, but they do tend to be on the shy side. Again Lynn has you covered I don't think I can offer any advice more than what she has already given you.

We would love to see some pics of the tank though!

Welcome to the forum!!!