The Grayling grows to a maximum recorded length of 60 cm (24 in) and a maximum recorded weight of 6.7 kg (15 lb). It has5–8 dorsal and 3–4 anal spines, which are absent in the other species; T. thymallus also has a smaller number of soft rays in these fins. Individuals of the species have been recorded as reaching an age of 14 years.
The grayling prefers cold, clean, running riverine waters, but also occurs in lakes and, exceptionally, in brackish waters around the Baltic Sea. Omnivorous, the fish feeds on vegetable matter as well as crustaceans, insects and spiders, molluscs, zooplankton, and smaller fishes, including Eurasian minnows.
T. thymallus is one of the economically important Thymallus species, being raised commercially and fished for sport.
The grayling is a protected species listed in appendix III of the Bern Convention. It is native to some areas of England and Wales, it was first introduced into parts of Scotland 150 years ago.