Congrats on the new froggy, I too have a new gray tree frog in a 10 gal...about to make it vertical for more height for the little guy, I am new to this but I would have to say I wouldn't put more than 2 in that size...maybe someone else thinks differently though...also they will tell you religiously not to combine a new froggy without quarantining him first to check for parasites gotta check the poo...lol