10 20 40 60 cm
mittakaava < 60 cm
Gösta Sundman: Suomen Kalat (Kansalliskirjasto, The National Library of Finland), Lauri Urho, Jouko Lehmuskallio
Thymallus thymallus (L.)
- Family: Salmonids – Salmonidae
- Similar species: whitefish, vendace
- Size: In northern Finland usually 30–40 cm, in central and southern Finland up to 40–50 cm and weight c. 1 kg. Grayling over 60 cm and weighing more than 2 kg are rare.
- Appearance: With its tapered, streamlined body, the grayling resembles the whitefish. Distinguished from other salmonids by its large sail-like dorsal fin, which has 17–24 rays. Like all other members of the salmon family the grayling has an adipose fin. The mouth is rather small. Reputed to have a smell like the herb thyme, from which it derives its Latin name Thymallus.
- Colouring: Varies with habitat. Grayling from clear waters are lighter in colour with slivery grey sides, while those from peaty waters may be more brown, green or even tinged with violet. Sides and dorsal fin display rows of diffuse dark spots. Spawning males acquire more showy colours with redder spots on the dorsal fin.
- Reproduction: Spawning usually takes place in flowing water. Populations spawning in lakes and the northernmost Gulf of Bothnia seek shallow, gravelly bottoms. Some of these fish run rivers to spawn. Unlike other salmonids, grayling spawn in the spring.
- Food: Insect larvae, other bottom invertebrates and surface insects.
- Distribution and habitat: Found throughout Lapland with the exception of lakes in the highest fells. Also occurs in the Vuoksi river system in SE Finland and in the northernmost Gulf of Bothnia. Prefers fast-flowing, streamy water; in lakes and the sea grayling seek out rocky shores and shallows where there is moving water. Grayling have been successfully introduced into central and southern Finland, and can be found in some waters as far south as the coast of Uusimaa province.
- Endangerment: Grayling’s sea stands are classified as critically endangered and inland waters’ stands in South-Finland near threatened.
Grayling make good eating and are also highly rated as a sporting fish. Primarily a fish of fast flowing water, grayling are a favourite with fly fishers, as even large specimens will rise willingly to small flies. Today, anglers can fly fish for grayling in the river Kymi in SE Finland and even in Helsinki’s neighbouring city Vantaa, where a breeding population has been established. However, original populations are under threat from river construction and water pollution. Grayling require well oxygenated water and are poorly tolerant of acidification.