Alewife

The alewife or river herring (Alosa pseudoharengus) is an anadromous species of herring found in North America. It is one of the "typical" North American shads, attributed to the subgenus Pomolobus of the genus Alosa. As an adult it is a marine species found in the northern West Atlantic Ocean, moving into estuaries before swimming upstream to breed in freshwater habitats, but some populations live entirely in fresh water. 

Main Photo Credit: 
"Alewife (Alosa pseudoharengus), Ontario, Canada" by Jack Toms, 2025. CC BY-NC 2.0.

Description: Wikipedia