Ketu is the rest of the body of Rahu, it bestows spiritual tendencies, asceticism, and nonattachment to worldly desires and ambitions. Ketu is also a half-planet that bestows wisdom, powers of discrimination, and gyana-spiritual knowledge, the knowledge of the self. It gives psychic abilities to its natives and makes them masters of the healing arts, natural healing, healing herbs, spices, foods, tantric healing, healing persons affected by evil spirits and ghosts.
Ketu's sign is Pisces - as Rahu's is Virgo. The sign Pisces belongs the the guru, Jupiter, and Ketu also has dominion over it.
Ketu's body is supposed to be composed of a man's torso in its upper half and a fish body as its lower half.