Northcote, T.G. (1995) Comparative biology and management of Arctic and European grayling (Salmonidae, Thymallus). Rev. Fish. Biol. Fish., pp. 141-194
| Species | Development state | Trait | Primary Data | Secondary Data |
| Thymallus thymallus | Egg | Oocyte diameter | 2.5-3.5 | 3.0 mm |
| Thymallus thymallus | Egg | Egg size after water-hardening | 4.0 [After fertilization] | 4.0 mm |
| Thymallus thymallus | Egg | Temperature for incubation | 8.5-9.0 | 8.75 °C |
| Thymallus thymallus | Egg | Degree-days for incubation | 180-220 | 200.0 °C * day |
| Thymallus thymallus | Larvae | Initial larval size | 10-12 | 11.0 mm |
| Thymallus thymallus | Larvae | Larvae behaviour | At 12-18°C, larvae spend 5-10 days in the gravel | Demersal |
| Thymallus thymallus | Larvae | Reaction to light | The fry emerge from the gravel during the day, with a peak shortly after sunrise | Photopositive |
| Thymallus thymallus | Female | Age at sexual maturity | Most 4-5, but in some areas at 3 [Female] | 4.5 year |
| Thymallus thymallus | Female | Relative fecundity | 10-31 | 20.5 thousand eggs/kg |
| Thymallus thymallus | Male | Age at sexual maturity | Mostly 3-4, but some at 2 [Male] | 3.5 years |
| Thymallus thymallus | Spawning conditions | Spawning season | March or April to June | ['March', 'April', 'May', 'June'] |
| Thymallus thymallus | Spawning conditions | Spawning temperature | 4-7, but sometimes up to nearly 15 | 5.5 °C |
| Thymallus thymallus | Spawning conditions | Spawning water type | Fast-flowing tributaries, streams [Water velocities range from 23 to 90 cm/s] | Flowing or turbulent water |
| Thymallus thymallus | Spawning conditions | Spawning depth | Shallow | No data |
| Thymallus thymallus | Spawning conditions | Spawning substrate | Fine gravel, gravel but also sand or stones | Lithophils |
| Thymallus thymallus | Spawning conditions | Nycthemeral period of oviposition | Latter part of the day near the diel temperature maximum | Day |
| Thymallus thymallus | Spawning conditions | Parity | Seem to spawn almost every year | Iteroparous |
| Thymallus arcticus | Egg | Oocyte diameter | 2-3 [Prior to fertilization] | 2.5 mm |
| Thymallus arcticus | Egg | Egg Buoyancy | Heavy | Demersal |
| Thymallus arcticus | Egg | Egg adhesiveness | Slightly adhesive | Adhesive |
| Thymallus arcticus | Egg | Incubation time | 16-18 days at 9°C | 17.0 days |
| Thymallus arcticus | Egg | Temperature for incubation | 9.0 | 9.0 °C |
| Thymallus arcticus | Egg | Degree-days for incubation | 156-181 | 168.5 °C * day |
| Thymallus arcticus | Larvae | Initial larval size | 7-11 up to 15 at emergence ! | 9.0 mm |
| Thymallus arcticus | Larvae | Larvae behaviour | First 3-4 day period of sub-gravel residence for hatched larvae | Demersal |
| Thymallus arcticus | Female | Age at sexual maturity | Most at 4-5, few at 3 and rarely at 2 [Both sex] | 4.5 year |
| Thymallus arcticus | Female | Relative fecundity | Average 10, range 6.475-16.887 | 11.68 thousand eggs/kg |
| Thymallus arcticus | Female | Absolute fecundity | 1.120 and 1.226 eggs for females of 197 and 219 mm respectively | 1.12 thousand eggs |
| Thymallus arcticus | Male | Age at sexual maturity | Most at 4-5, few at 3 and rarely at 2 [Both sex] | 4.5 years |
| Thymallus arcticus | Spawning conditions | Spawning migration period | Move onto spawning areas shortly after ice-out at temperatures near 4°C, usually in May | ['May'] |
| Thymallus arcticus | Spawning conditions | Spawning season | Spring spawners: May, but vary from April to as late as July | ['April', 'May', 'June', 'July'] |
| Thymallus arcticus | Spawning conditions | Spawning period duration | 3-4 [Early to late May] | 3.5 weeks |
| Thymallus arcticus | Spawning conditions | Spawning temperature | 5-9 | 7.0 °C |
| Thymallus arcticus | Spawning conditions | Spawning water type | Use mainstream river tributaries and sidechannels, rarely in lakes [Flows of 0.5-1.0 m/s] | Stagnant water |
| Thymallus arcticus | Spawning conditions | Spawning depth | 10-40 cm | 25.0 m |
| Thymallus arcticus | Spawning conditions | Spawning substrate | Over stable coarse gravel (2-4 cm) | Lithophils |
| Thymallus arcticus | Spawning conditions | Spawning site preparation | Altough redds are not constructed or covered by the female, in some cases shallow pits may appear in the stream as a result of prespawning activity [Males set up and hold spawning territories of 6-7 m²] | Susbtrate chooser |
| Thymallus arcticus | Spawning conditions | Nycthemeral period of oviposition | Most spawning is said to take place in mid to late afternoon, but some said that most spawning occurred in evening or night | Night |
| Thymallus arcticus | Spawning conditions | Parity | Grayling may spawn every year | Iteroparous |