"The fish is the living symbol of Primitive, Gnostic Christianity. The two fish of Pisces linked by a hyphen have a profound Gnostic significance; they represent the two Souls of the primordial Elohim submerged within the deep waters of Mother-Night... It is a pity that thousands of students of occultism have forgotten the Gnosis of the fish." - Samael Aun Weor, The Esoteric Treatise of Hermetic Astrology
Also, study the Hebrew letter Nun.