Potamorrhaphis is a scientific term used to describe a fish that is able to move between freshwater and saltwater habitats. There are several synonyms for this term that are commonly used in different contexts. These synonyms include diadromous, amphidromous, and catadromous. Diadromous fish migrate between freshwater and saltwater habitats for various reasons such as reproduction or feeding. Amphidromous fish only migrate between these habitats during their larval stage. Catadromous fish, on the other hand, migrate from freshwater to saltwater habitats for spawning purposes. Understanding these synonyms can help scientists and fish enthusiasts better classify and understand different types of fish species and their behaviors.