The Lower Cretaceous Crato and Santana formations have provided one of the richest Mesozoic fish faunas from South America. An updated review of this ichthyofauna, comprising, 28 nominal species, is presented here. Contrary to the previous idea that the Araripe Basin had an endemic fauna related to the opening of the South Atlantic Ocean, it is now accepted that this fauna is instead related to that of the Tethys. A marine connection with the Araripe Basin is indicated by the presence of species closely related to those of other assemblages occurring in the western part of the Tethys. However, the absence of marine invertebrates suggests non-marine conditions for this basin, with only intermittent connections to the epicontinental seaway. Some of the fishes found in the Crato Formation are juveniles of the species found in the Santana Formation, suggesting several important paleoecological implications related to the reproduction of these fishes and using there as a nursery.