Water tigers are an unknown type of big cat that allegedly inhabits the Amazon River basin. Like jaguars, they are said to have a wide range of coat colours and are frequently described as having black, reddish or light brown, and even white fur. Unlike jaguars, water tigers are said to be semi-aquatic, not known in any cat species in the Americas. They are also frequently described as having a short, cow-like tail, long canine teeth, and webbed toes. In both folklore and written accounts, water tigers are unusually aggressive towards humans.
Numerous names exist for the water tiger, such as entzaeia-yawa, meaning "water panther' in the Native Ecuadorian Shuar language, aypa, in the Brazilian states of Pará and Amapá, and maipolina, which is used in French Guiana.
In 1994, Author Christian Voillemont mentioned that a Wayampi man killed a sabre-toothed "giant otter" in the Oyapock River. Voillemont also wrote about a deadly water tiger attack. A Wayampi tribesman told him that one of his colleagues was killed by a water tiger. He claimed that the creature suddenly burst out of the water, destroyed his canoe, and took off with him.
Spanish cryptozoologist Angel Morant Forés described a story that was told to him by Carlos Pichama, who claimed that his wife was fatally mauled by a water tiger and dragged into the river. The next day, he and his siblings threw dynamite into the river, in the hope of killing the creature. Sure enough, the corpse of a large, cat-like creature with long, red fur rose to the surface.
Forés speculates the water tiger may be a misidentified giant river otter, which is vaguely cat-like and can grow to over eight feet long from tail-to-tip, although giant river otters are not particularly aggressive to humans, nor do they have large canine teeth. Giant river otters also have a white patch on their chest, which the water tiger lacks.
French cartoonist and author Philippe Coudray speculates it may be some kind of surviving Smilodon, commonly referred to as sabre-tooth tigers. Although water tigers do have massive canine teeth and short tails, there is no evidence to suggest smilodons were semi-aquatic.