Giant River Otter is the largest member of the mustelid family. The mustelid family is an animal that has short legs, a long thin body, thick fur, and anal scent that includes the weasel, badger, otter, mink, marten, polecat, and wolverine.In the wild Giant River otters eat fish, and crustaceans. They are picky, and every single tooth in their mouth is pointed to help them eat the entire fish. Giant River Otters eat fish, rainbow trout, catfish, tilapia, herring squid, and yellow perch. The Giant River Otter has the shortest fur in all otter species; it is typically chocolate brown, but may be reddish or fawn, and appears nearly black wet.. [diurnal], and they are semi-aquatic, meaning they need both land and water habitat to survive. Never get close to a Giant River Otter, they have been known to attack humans, and females that are young.