Complex sentence: River stingrays are the only family of batoids completely restricted to fresh water habitats; while there are true freshwater species in the family Dasyatidae, for example "Himantura chaophraya", the majority of species in this family are saltwater fish.
Split into simpler sentences: River stingrays are the only family of batoids completely restricted to fresh water habitats. While there are true freshwater species in the family Dasyatidae, for example "Himantura chaophraya", the majority of species in this family are saltwater fish.