- Larger than the mink and American marten, the fisher's long fur makes its pelt valuable, especially that of the female. Like the American marten, the fisher is easy to trap.
- This furbearer is dark brown with a bushy tail, short legs, large feet, a wide head, a pointed snout, and small ears.
- Although it is a good swimmer, the fisher usually does not eat fish – contrary to its name. Instead, the fisher's primary food is porcupines, and it may spend two or three days feeding on one until the entire porcupine has been eaten.
- The fisher can be found in dense forests with coniferous trees or a mixture of coniferous and hardwood trees. It usually nests up high in hollow trees.
- Fishers are blind when born. When they are three or four months old, they are weaned from their mother. The male does not help raise the young.
- This is a very active animal, running along trails and logs. A good climber, it uses branches to move from tree to tree. It hides in holes, crevices, or underbrush.
- Mating: probably polygamous.
- Breeding period: March to April.
- Gestation period: almost 1 year.
- Birth period: late March to early April.
- Litters per year: 1.
- Number of young: 1 to 6 per litter; average 3.
- Age females can breed: 1 year.
- Adult weight: 3 to 12 pounds; male is about twice the size of the female.
- Life expectancy: about 10 years.
- Feeding time: primarily nocturnal but may be active during the day.
- Movement: home range 10 square miles but may go 50 to 150 square miles.
- Typical foods: porcupines, snowshoe hares, small mammals, carrion, birds, fish, insects, fruit, and nuts.