* In full: dish tirsi, i.e. toothy shad, in distinction from karagôz tirsi, i.e. black-eyed shad (Alosa alosa). The alternative spelling is tersi.
Maximum length 54 cm. Has half a dozen or so spots along the side. Fallax means false. The allis shad or true alose (Alosa alosa (Linnaeus)) lacks the spots and is not so common in the Mediterranean. Both enter rivers in the spring to spawn and the twaite shad may even live permanently in fresh water. Both are present, but not plentiful, in British waters.