Question: "What does the Christian fish symbol mean (ixthus / icthus)?"
Answer: The Christian fish symbol is one of the most ubiquitous symbols of Christianity. Apart from the cross, the fish symbol is probably the most recognizable symbol of faith. It is found on cars, Bible covers, tattoos, and more. The link between Christ and a simple line drawing of a fish is not readily apparent and requires a little explanation.
Briefly, the fish symbol is based on a Greek acronym for the phrase Jesus Christ, God’s Son, Savior. In Greek, the phrase is Ίησοῦς Χριστός, Θεοῦ Υἱός, Σωτήρ . When we take the first letter from each word in that phrase, we have ΙΧΘΥΣ, which happens to be the Greek word for “fish” (ixthus or icthus—the spelling can vary in English). Some versions of the Christian fish symbol contain the Greek letters inside or underneath the symbol itself.
The Christian fish symbol also brings to mind several events in Jesus’ ministry. Twice, Jesus provided a miraculous draught of fish for His disciples (Luke 5:4–7; John 21:4–6). He ate fish with His disciples on at least two occasions after His resurrection (Luke 24:42; John 21:13). The miracle of the temple coin involved a fish (Matthew 17:27). And of course the feeding of five thousand and the feeding of the four thousand started with a lunch that included fish (Matthew 14:15–21; 15:32–38).
During the early days of Christianity, Christians were often put to death for practicing their faith, so they worshiped in secret places. A fish painted or etched on the outside door of a house let other Christians know that they would be safe and welcome inside. The ancient catacombs in Rome are filled with images of fish, carved there by Christians hiding from persecution.
Jesus Christ, God’s Son, Savior is a wonderful summary of biblical truth regarding the Lord, and the Christian fish symbol is a beautiful way to express faith in Him. But following Christ involves much more than sporting an ixthus on the back of one’s car. Jesus spoke often of the necessity of inward truth as opposed to outward shows of religion. Those who use a Christian fish symbol should make sure they actually know Christ, trust Him as Savior, and obey Him as Lord.