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
Ide (fish) the wild in at least one site within New Zealand. Ide occurs in schools in the clear pools of larger rivers, ponds, and lakes but they may move to deeper waters during the winter before moving into shallow freshwater to spawn in the spring. The species is also found in the Baltic Sea, which has a lower salinity than most seas and in Sweden the fish spent the first year of their lives in rivers before joining the more mature fish as they migrated downstream into the Baltic Sea during the summer months. The fish then returned to the rivers