::It is only partially true, the frog does not eat only fruits. Of the frogs that were sampled only 14 percent head only fruits and their stomachs, while 27 percent had only arthropods. The frog's apparently capable of digesting four species of berries and a player role in those species seed dispersal. And apparently this is not the usual case of secondary ingestion, two individuals were maintained in captivity for four months on a diet exclusively of the fruits and subsisted on it.
:: ::Helio, R. da Silva, Monica C. de Brittopereira, and Ulisses Caramaschi. 1989. Frugivory and seed dispersal by Hyla truncata, a neotropical tree frog. Copeia. 3:781-783.