Arctic char can be either anadromous – living in the ocean and spawning in freshwater streams – or populations can be landlocked and remain in fresh water their whole life. They closely resemble salmon in appearance, but are closer genetically to lake trout. Their color depends on the time of year and environmental conditions of their habitat, ranging from pale pink or silver to bright red. Farmed char have skin that is red with cream-colored spots whereas wild char has more silver-colored skin. Optimal temperature for aquaculture practices is found to be around 54 degrees Fahrenheit (12 degrees Celsius), as this supports high growth rates, good feed utilization, a reduced risk of contracting diseases, and low fungus growth compared to higher temperature studies. Arctic char can tolerate high population densities without negative effects on feed intake or growth. The species thrives best in cold, clear, oxygen-rich water, and the entire production cycle can take place in a solely freshwater environment, although some farms choose to give populations a saltwater period.
Anadromous stocks grow much faster than freshwater populations, and begin spawning between four and ten years old. Freshwater stocks begin spawning between two and five years old. Arctic char can weigh up to 20 pounds; however, marketed fish are typically between two and five pounds.
Spawning occurs from September to November. During this season, males develop a hooked jaw and turn bright red, whereas females remain silver. Most males defend territories and mate with several females. The females dig nests, known as redds, where they deposit 3,000 to 5,000 eggs at a time. Char do not die after spawning like salmon, and often spawn every third to fourth year. Adults remain in the river for one to three years before returning to sea and young char remain for five to seven months, although some may remain for one to nine years. The use of temperature and light manipulation has enabled modified aquaculture spawning. Arctic char remain in the hatchery until they weigh 5-100g, and reach market size 15 to 30 months after hatching.
Char diet varies with season. In the late spring and summer, they eat aquatic insects, salmon eggs, snails, and small crustaceans and fish. During the autumn and winter months, char feed on zooplankton, freshwater shrimp, and small fish. In many cases, during the winter, char live off of the fat they accumulate in the summer. Larger char, found in late summer or fall, have more oil, and hence more flavor.