"Fish" is another frequently mistranslated word in the Bible. Its reference is often not to the form of swimming life, but to the symbol by which early Christians could identify each other. It was a secret sign, needed in times of persecution, prior to official acceptance of Christianity as a state religion.
The sign of the fish was a mystical symbol and conversational password. Its name deriving from the Greek word for fish, "ichthus" Much later it was represented an acrostic, composed of leading letters of the Greek phrase, "Iesous Christos Theou Uios Soter"-"Jesus Christ, Son of God, Saviour."
Frequent references to fish are intended as symbolic of The Christ and have nothing to do with the act of eating a dead fish. But the symbol of the fish did not meet with Roman approval. They preferred the sign of the cross, choosing to concentrate more on the death of Christ than on His brilliant life. Perhaps this is one reason only ten percent of His life record appears in the canonical scriptures. Most of His first thirty years has been omitted. Text quoted from: http://www.thenazareneway.com/thou_shalt_not_kill.htm
"Lay down your nets and follow me," Jesus said, "and I will make you fishers of men." At once they left their nets and followed him. http://www.thenazareneway.com/index_vegetarian.htm