Syngnathus is a genus of fish in the family Syngnathidae found in marine, brackish and sometimes fresh waters of the Atlantic, Indian and Pacific Ocean. Fossils of these species are found from the Oligocene to the Pleistocene. They are known from various localities of Greece, Italy, Germany and United States.

The Syngnathidae is a family of fish which includes seahorses, pipefishes, and seadragons. The name is derived from Ancient Greek: σύν, meaning "together", and γνάθος, meaning "jaw". The fused jaw is one of the traits that the entire family have in common.