The mermaid with the body of a woman and the tail of a fish is a symbol for fertility, eternal grace and beauty. As with many water creatures she is associated with the moon, mystery, and the unconscious. Residing in the cosmic ocean from which all life has emerged and into which it must eventually return, the mermaid also represents renewal, purification, wisdom, and infinity.
Sexually tantalizing and devastatingly lovely, mermaids are perfect symbols for feminine (yin) power. This is quite nice, as mermaids also represent wild freedom, rebellious spirits and ferocious independence (they can never be contained and frequently avoid settling).