if he is only two inches I would try giant danios because he wont catch those. at least not yet. ive had giant danios and ive had silver dollars. each in a 4' tank. and silver dollars are way to wild for me. always slamming into everything in the tank. including the walls of the tank. but giant danios are way more controlled swimmers. their movements are way less sporadic.
i would go with giant danios.
but i honestly think anything you add will eventually be killed.
Well I'll debate on it, anyway he is supposed to be a wet pet but I would love a little movement in the tank if possible though! Here he is btw

