assumeing fresh water REAL fire belly newts (some newts labeled as fire bellies look totally differnt and can get big maybe a problem), also aquatic frogs dwarf, plus fire bellie toads toads, most amphibians are to slow to bug the fish, try to stick with faster fish if you can i don't realy know of amphibians that would be a problem, heve heard of dwarf frogs as agressive but probally only when hungry cause mine are very docile and chubby
But watch out with keeping multiple species of amphibians toghether, especially if they are hungry cause they will try to eat anything they can catch, firbellies newts (real one no bigger than pinky) and aquatic frogs would probally be your safest for a community aquarium