The Goosander (mergus merganser) is a large, attractive "sawbill" duck that may be found mostly on freshwater areas of Britain and Ireland. It is also known as the Eurasian Goosander, Eurasian Merganser, European Goosander, the Common Merganser in North America, American Goosander and Sawbill.

The Goosander is a slim, thin-billed fish-eating duck with a large head, crest and neck. Adults measure 57 to 69 cm (or 22.4 to 27.2 inches) long and weigh between 1.0 and 1.6 kilograms (or 2.2 and 3.5 pounds).

Males and females are not alike. The drake has a glossy green-black head and back and pale salmon-pink underparts in the breeding season. The male has a noticeable mane of feathers on the back of the neck. The thin bill and legs are red.

The female is slightly smaller and mostly grey, with a chestnut head and white chin. The beak is bright orange with a black tip. The eyes are yellow. The rump and tail are grey.

Females and non-breeding males have crests on their heads, although the crest is shorter in females. Immature birds and non-breeding males resemble females but have a white stripe between the eye and bill.

The male's call is of a low-pitched croaking and the female makes a harsh "krr" and crackling sound. Adults start breeding when they are 2 years old. The average lifespan of these ducks is 7 years.

It is the largest member of the "sawbill" family of ducks. "Sawbills" earned their name because of the edges of their beaks have fine serrations, like a saw, that are designed to hold slippery fish. There is a hook at the end of the beak. They resemble their close relative the Red Breasted Merganser but a larger and heavier bird.

Goosanders are sociable ducks who inhabit mostly clear freshwater inland areas such as lakes, rivers, reservoirs and flooded gravel pits throughout the year. They are also found in estuaries, along streams near the coast or on the coast. Breeding takes place near water on the shores of lakes and rivers, usually in the hollow of a tree. Most birds are resident although males fly to Norway in late summer for their annual moult.

Their diet is a wide range of small to medium fish (salmon, sandeels, trout, chubb, eels, rudd, tench, perch, sticklebacks). Invertebrates (shellfish, insects and their larvae, snails), crustaceans (crabs, crayfish) and other prey (amphibians) are sometimes taken.