They owe these bad qualities most of all to their relationship with the mother- and love-goddess Ishtar, Astarte, Atargatis, or Aphrodite. As the planet Venus, she has her ‘exaltatio’ in the zodiacal sign of the fishes.
Jung identifies Atargatis as one of the mother-and-love-goddesses whose numinous eroticism and voracity are the ultimate source of the fish’s opprobrious yet sacred symbolic qualities in the Pisces aeon.
, Aion: Researches into the Phenomenology of the Self, 1951thesis