Pisces & the Christian Symbol of the Fish

Due to the earth's precession the Vernal Equinox gradually moved from Aries the ram to Pisces the fish sometime vaguely around 1 CE to 300 CE. (Since there are no well defined borders between the zodiac constellations there's no definitive date.) Hence the symbol of a fish, representing Pisces, became the symbol of Christianity, because the Sun was in Pisces, the fish, on the Vernal Equinox.

Sometimes the fish symbol has the Greek letters ΙΧΘΥΣ in it. This is just the Greek word for "fish" (see Strong's Greek #2486). Some people though have made use of the letters of the word as an acronym for a clever phrase.

The symbol of the fish is also found in the miter the Pope wears. (See the fish in the side view?)

As for Christ on the cross, the oldest artistic representations of the Christian cross depict a figure of a lamb (Aries). The practice of symbolising the saviour by a lamb continued until the Council of Constantinople (692 CE) under the pontificate of Agathon and during the reign of Constantine Pogonat. It was decreed that, instead of the ancient astrological symbol of Aries the lamb, all crosses depicted in art should be combined with the figure of Jesus. The retiring of the Lamb as the main Christian symbol, translated from the Latin, is as follows:

In the Roman Sotteranea of Antonio Bosio, concerning the image of Christ under the figure of a lamb:

In certain representations of the images of the saints, a lamb is portrayed. We, therefore, accepting the old forms and shadows as signs of the truth and as traditional symbols of the church, prefer Grace and Truth, which we accept as the fulfilment of the Lamb. So, that which is perfect, let us place in pictures, even before the eyes of all. We have decreed that the Lamb, which taketh away the sins of the world, Christ our God, ought to be portrayed henceforth in human form in place of the Lamb.
(Higgins, Anacalypsis, Vol.2, pp.111-112)

At first, Jesus was represented fully robed, standing calmly before the cross with outstretched arms. The lamb continued to be shown, usually at the foot of the cross. Later, the figure of Jesus was placed on the cross, undraped, bleeding and tortured by pain from wounds, as he is represented on crucifixes today. Pope Adrian I confirmed this point.¹

12. Due to earth's precession the Sun is now in Pisces the fish on the Vernal Equinox.
[A fish is now the symbol of Christianity.]

[1] Larry M. Wright Christianity, Astrology and Myth pg. 79