The fish had already become an identifying symbol among early Christians well before any writer connected it to a zodiacal age: the ichthys, a simple two-arc fish outline, and the Greek acrostic built from the word for fish, spelling out "Jesus Christ, Son of God, Savior," both circulate in the first centuries CE, alongside the Gospel accounts of Jesus calling fishermen as his first disciples and multiplying loaves and fish. The later reading, chiefly associated with Jung's Aion and the wider ages literature Nicholas Campion surveys, treats this cluster of fish symbolism as evidence that the rise of Christianity coincided with the opening of the Age of Pisces, though the fish symbolism itself has an ordinary, well documented origin in the disciples' occupation and in early Christian need for a covert identifying mark, independent of any astrological claim.
The age's end date, and by extension the question of whether the Age of Aquarius has already begun, is the single most contested point in the entire ages literature, with credible proposals ranging across several centuries; this entry states the range rather than adopting any one writer's date as settled. Some writers who divide the Great Year by the true, unequal width of the constellations rather than by an even 2,150 year span place the Pisces to Aquarius transition centuries earlier than the even-division estimates, while others place it centuries later, and no single method has become the field's accepted standard, which is why claims that the Age of Aquarius has already definitely begun, or definitely has not, should both be read as one writer's position rather than an established fact.