The two fishes are joined by a long cord knotted at the star Alrisha, the knot, and the Babylonian tradition already recognised two fish figures here. The Greek story makes them Aphrodite and Eros, who took the form of fishes and tied themselves together so as not to be separated while escaping the monster Typhon. The constellation matters out of proportion to its faintness for one astronomical reason: because of precession, the vernal equinox, the tropical zero point of Aries, has lain within the stars of Pisces for roughly the last two thousand years, and is now moving toward Aquarius. Early Christian use of the fish as a symbol is documented from the second century and rests on the Greek acrostic ICHTHYS; the further claim that it was chosen because of the precessional age is a modern interpretation and is not attested in the early sources.
Manilius and other Latin sources note the sign's traditional weakness and passivity, reading the bound fishes as figures without power of their own motion, dependent entirely on the cord that joins them, an image some modern commentators connect, more as a later resonance than a documented ancient claim, to Pisces's role as the final and most dissolving sign of the zodiac's own cycle. The ICHTHYS acrostic, Iesous Christos Theou Yios Soter, Jesus Christ Son of God Saviour, functioned in the earliest Christian centuries chiefly as a covert recognition symbol during periods of persecution, a practical rather than an astrological use of the fish image that had nothing to do with the sign's zodiacal associations in its own earliest attestations.