Just what exactly does it mean? Ichthus or ichthys is a Greek word that simply means ‘fish’. Mark 1:17: "Come after Me, and I will make you become fishers of men."

 The Greek spelling for Ichthus is IXOYΣ (Iota, Chi, Theta, Upsilon, and Sigma). The five letters IXOYΣ are an acrostic for Iesous Christos, Theou Uios, Soter rendered into English meaning, Jesus Christ, Son of God, Savior.

 Often times the Christian Fish is displayed with the letters IXOYΣ inside the fish. The Ichthus can also be represented by a six spoke wagon wheel created when the letters IXOYΣ are displayed all on top of each other. The E must be like an Σ and the horizontal lines a bit curved.

Used as a code or secret handshake?

 It is said that during a period of the Roman Empire (54 A.D.  – 307 A.D.) the Ichthus may have been used by Christians to avoid persecution. If a Christian was unsure of whether he was in good company he might casually draw a single arc of the Fish in the sand giving a fellow believer the opportunity to complete the other arc. A non-Christian probably would not recognize the single arc as anything significant, dismissing it as a simple doodle.