River otters are semi-aquatic mustelids that can be found in any fresh water environment. They are excellent swimmers and prey on slow moving fish, crayfish, and frogs. Otters are the most playful animals known, spending a considerable amount of time idly amusing themselves. They seem to particularly enjoy sliding down mud and snow banks. The forepaws of river otters are moderately dexterous, capable of grasping and a limited manipulation.
River otters are often considered pests by fishermen, who believe the otters depleat game fish. In fact, they rarely take the faster moving game fish, preferring the slower moving species. This antipathy of fishermen combined with their luxurious and valuable fur, water polution, overuse of pesticides, and the draining of wetlands has led to the decline of otters in many areas around the globe.