The brook trout has a dark green to brown color, with a distinctive marbled pattern (called vermiculation) of lighter shades across the flanks and back and extending at least to the dorsal fin, and often to the tail.
A distinctive sprinkling of red dots, surrounded by blue halos, occurs along the flanks.
The belly and lower fins are reddish in color, the latter with white leading edges.
Often, the belly, particularly of the males, becomes very red or orange when the fish are spawning.

Typical lengths of the brook trout vary from 25 to 65 cm (9.8 to 25.6 in), and weights from 0.3 to 3 kg (0.66 to 6.61 lb).
The maximum recorded length is 86 cm (34 in) and maximum weight 6.6 kg (15 lb).
Brook trout can reach at least seven years of age, with reports of 15-year-old specimens observed in California habitats to which the species has been introduced.
Growth rates are dependent on season, age, water and ambient air temperatures, and flow rates.
In general, flow rates affect the rate of change in the relationship between temperature and growth rate.
For example, in spring, growth increased with temperature at a faster rate with high flow rates than with low flow rates.
The brook trout has a dark green to brown color, with a distinctive marbled pattern (called vermiculation) of lighter shades across the flanks and back and extending at least to the dorsal fin, and often to the tail. A distinctive sprinkling of red dots, surrounded by blue halos, occurs along the flanks. The belly and lower fins are reddish in color, the latter with white leading edges. Often, the belly, particularly of the males, becomes very red or orange when the fish are spawning.
Typical lengths of the brook trout vary from 25 to 65 cm (9.8 to 25.6 in), and weights from 0.3 to 3 kg (0.66 to 6.61 lb). The maximum recorded length is 86 cm (34 in) and maximum weight 6.6 kg (15 lb). Brook trout can reach at least seven years of age, with reports of 15-year-old specimens observed in California habitats to which the species has been introduced. Growth rates are dependent on season, age, water and ambient air temperatures, and flow rates. In general, flow rates affect the rate of change in the relationship between temperature and growth rate. For example, in spring, growth increased with temperature at a faster rate with high flow rates than with low flow rates.
Brook trout