Most commonly, the stories involve a type of freshwater dolphin which lives in the Amazon River called the Boto. It is larger and more primitive-looking than the other type of Amazonian dolphin, the Tucuxi.
There are three elements that best characterize encantados: superior musical ability, their seductiveness and love of sex (often resulting in illegitimate children), and their attraction to parties. Despite the fact that the Encante where they come from is supposed to be a utopia full of wealth and without pain or death, the encantados crave the pleasures and hardships of the human world.
Transformation into human form seems to be rare, and usually occurs at night. The encantado will often be seen running from a festa, despite protests from the others for it to stay, and can be seen by pursuers as it hurries to the river and reverts back to dolphin form. When it is under human form, wears a hat to hide its proeminent forehead, that does not disappear with the shapeshift.
Besides the ability to shapeshift into human form, encantados frequently wield other magical abilities, such as the power to control storms, "enchant" or haunt humans into doing their will or becoming encantados themselves, and inflict illness, insanity, and even death. Shamans and holy men are often needed to intervene and ameliorate the situation, but sometimes the spell is so great that it can not be completely cured.
Kidnapping is also a common theme in such folklore. Encantados are said to be fond of abducting humans they fall in love with, children born of their illicit love affairs, or just anyone near the river who can keep them company, and taking them back to the Encante. The fear of this is so great for many Brazilians that many people, children and adults alike, are terrified of going near the water, especially alone. Some who have encountered encantados out in canoes have been said to have gone insane, although the creatures seem to have done little more than follow their boats and nudge them from time to time.