Several life history forms of Arctic grayling occur: fluvial populations that live and spawn in rivers; lacustrine populations that live and spawn in lakes; and potamodromous populations that live in lakes and spawn in tributary streams.

The Arctic grayling occurs primarily in cold waters of mid-sized to large rivers and lakes, returning to rocky streams to breed.
 The various subspecies are omnivorous.
Crustaceans, insects and insect larvae, and fish eggs form the most important food items.
Larger specimens of T. arcticus become piscivorous and the immature fish feed on zooplankton and insect larvae.

Spawning takes place in the spring.
Adult fish seek shallow areas of rivers with fine, sand substrate and moderate current.
Males are territorial and court females by flashing their colourful dorsal fins; the fins are also used to brace receptive females during the vibratory release of milt and roe.
The fish are nonguarders: the eggs are left to mix with the substrate.
Although the Arctic grayling does not excavate a nest, the highly energetic courtship and mating tends to kick up fine material which covers the zygotes.
The zygote is small (approximately 3 mm or 0.1 in in diameter) and the embryo will hatch after two to three weeks.
The newly hatched embryo remains in the substrate until all the yolk has been absorbed.
They emerge at a length of around 12 to 18 mm (0.5 to 0.7 in), at which time they form shoals at the river margins.
The juveniles grow quickly during their first two years of life.
Several life history forms of Arctic grayling occur: fluvial populations that live and spawn in rivers; lacustrine populations that live and spawn in lakes; and potamodromous populations that live in lakes and spawn in tributary streams.
The Arctic grayling occurs primarily in cold waters of mid-sized to large rivers and lakes, returning to rocky streams to breed.  The various subspecies are omnivorous. Crustaceans, insects and insect larvae, and fish eggs form the most important food items. Larger specimens of T. arcticus become piscivorous and the immature fish feed on zooplankton and insect larvae.
Spawning takes place in the spring. Adult fish seek shallow areas of rivers with fine, sand substrate and moderate current. Males are territorial and court females by flashing their colourful dorsal fins; the fins are also used to brace receptive females during the vibratory release of milt and roe. The fish are nonguarders: the eggs are left to mix with the substrate. Although the Arctic grayling does not excavate a nest, the highly energetic courtship and mating tends to kick up fine material which covers the zygotes. The zygote is small (approximately 3 mm or 0.1 in in diameter) and the embryo will hatch after two to three weeks. The newly hatched embryo remains in the substrate until all the yolk has been absorbed. They emerge at a length of around 12 to 18 mm (0.5 to 0.7 in), at which time they form shoals at the river margins. The juveniles grow quickly during their first two years of life.
Arctic grayling