In the early days of the Christian church when Christians were being persecuted by the Romans, the fish became a symbol for Christians and what they believed.

"It is frequently found carved on the walls of the catacombs beneath the ancient city of Rome. The Greek word for "fish" is ichthus, and each letter represented a word, namely:

i Iesous--Jesus ch Christos--Christ th theou--of God u hulos--son s soter--savior

"The fish thus became a sort of code word during times of persecution, by which believers expressed the conviction, 'I believe that Jesus Christ is the Son of God and my Savior.'"

-- Source: KneEmail http://www.oakhillcoc.org