Final answer:
The astrological creature known as Capricorn is depicted as half fish and half goat, a zoomorphic symbol found in various ancient cultures.
Step-by-step explanation:
The astrological creature often described as being half fish and half goat is the Capricorn. In astrology and mythology, Capricorn is represented by a creature that has the body and tail of a fish and the head and torso of a goat. This symbol is rooted in the imagery and stories of various ancient cultures, where zoomorphic or hybrid creatures were common in art and lore. One of the well-known examples is the centaur in Greek mythology, featuring a blend of human and horse characteristics.