I used to keep paradise fish and they ate anything that came lose to fitting in their mouths. I fed them guppies of all sizes, tadpoles, tiny little frogs. The tadpoles were way to big to fit in their mouths but tadpoles are so fragile that the fish would latch on and suck their guts out. The frogs took longer to eat and they would swim around with frog legs sticking out their mouths.
They are definitaly no good for small tank mates. mine got along well with similar size firemouths and gouramis