The Fifth Sunday after Trinity Gospel in the 1928 BCP is Luke v.1 In it Jesus sent Peter for the big catch, and then told him:
from henceforth thou shalt catch men
This, and other Gospel accounts concerning fish, influenced the ancient Church. The Apostles as a group came to become known as "fishers of men", and Christians as "Pisciculi" the root word being fish. The fish was and still is a symbol, along with the cup and bread, of the Christian communion (At the Legion HQ, the communion paten is inscribed with a large Ichthus fish symbol.) The fish also became a security sign for persecuted Christians. One person meeting another would mark and arc - 1/2 of the fish, and the other Christian would complete the symbol - perhaps still a fitting mark for Christians even in this electronic age. The sign was often used to indicate where Christians would assemble. The fish became a symbol of Christianity and the Greek word Ichthus, meaning fish, an acrostic for a summary of the belief in Jesus: The letters were assigned as follows: Iesous (Jesus) CHristos (Christ) THeou (of God) Uiou (the Son) Soter (the Savior). Ichthus became a hidden form of confession for the Christian. In recent years this symbol and acrostic has seen a revival as a form public confession and identifying places where Christians assemble and work. The Ichthus may have formed the basis for the Jesus Prayer. In Eastern Church the Jesus prayer is the model for continuous prayer. In the Western churches, it is sometimes used in prayer with Rosary devotions. Centurions may also use the ancient acrostic as part of the liturgy of the daily Devotion: "Lord Jesus Christ, Son of God, Savior, have mercy on us".
sources included religioustolerance.org
Visit the Order at www.OrderofCenturions.org