Twait shad are silvery, sometimes with a bronzy tinge, and there are a distinctive row of six to ten large dark spot just behind the gill cover though these may fade when the fish is dead. The adult length is typically . The twait shad is found in most of Europe and all countries bordering the Mediterranean Sea. "Alosa fallax" has a similar lifecycle to "A. alosa" (allis shad). They are known to live in sympatry. Some studies have suggested "A. fallax" and "A. alosa" species can hybridize. They are anadromous species, like many other species in the genus "Alosa". However, some
Alosa Most individuals die shortly after spawning. "Alosa" species are seemingly very adaptive vertebrates, so can change readily to adapt to their environments, as species are found in a variety of temperatures and waters. As "Alosa" species are generally anadromous, they are faced with various obstacles to survival. They may have to pass through numerous barriers and waters to get to either their spawning grounds or normal habitats (the sea in most cases). Estuaries are a major factor in numerous "Alosa" species' migration. Estuaries can be highly variable and complex environments contributing to fluctuating biological interactions, with shifts in osomolarity, food