You see them on cars and trucks everywhere. A large number of the vehicles in the church parking lot may have them displayed on bumpers and rear windows. It is a symbol that resembles the outline of a fish. Do these symbols identify the driver as a fisherman or fisherwoman? Does he or she worship fish for some reason? What is this symbol and where did it come from? Let us investigate a bit further.
My research, albeit brief, revealed that the history of this symbol is scarce, mostly conjecture. The New International Dictionary of the Christian Church says this concerning the use of the fish symbol as a symbol for Christianity, “Neither is it known how early this usage developed” (p. 377). We know that it represents Christianity now, but one would have to consult ancient primary sources for more information, if it even exists. Therefore, this article is mostly based on the popular opinions passed down from age to age.
The Greek word for ‘fish’ is ‘ichthus’ (transliterated from the Greek). The early Christians  formed an acrostic from these letters as follows: I= Iesous (Jesus); CH=Christos (Christ); TH=Theous (God); U= UIOS (Son); SOTER (Savior). Therefore, the idea of the fish, or the sight of the symbol, would immediately bring to the believer’s mind the good news of Jesus Christ. Combined with the fact that, during Jesus’ ministry, He referred to His disciples as “fishers of men” (Matthew 4:19; Mark 1:17) and He fed huge groups of His followers meals of fish (Matthew 14:13-21, 15:33-39; and parallel accounts), the fish was an excellent choice to represent the followers of Jesus.
The Necessity of the Early Symbol Use
The early Christians were persecuted by both the government and religious leaders of their day. Roman emperors often regarded themselves as gods and demanded that the people worship them as such. Therefore, this Christian religion, which worshiped Jesus Christ, was a threat to these emperors and their rule. These believers in Christ had to keep their beliefs hidden from the government because of this.
The Jews also believed that these Christians were worshiping a false god. Because Christians followed Jesus Christ, the Jewish religious leaders sought to squash what they believed to be a new, and blasphemous, religion. Hence, Christians had to hide the fact that they were followers of Christ from the Jewish leaders too.
The fish symbol was a way Christians could identify themselves to each other without either the government or the religious leaders recognizing them. Upon meeting someone new, a believer would draw half of the fish symbol in the dirt and the other person would either complete the other half of the symbol, thus revealing himself or herself as a Christian, or not recognize the action of the believer, thus revealing himself or herself as not being a believer. Since the non-believer did not recognize the believer’s actions, the believer’s religious beliefs could remain safely hidden.
Present Day Usage
The fish symbol’s importance in the United States seems to be more decorative than anything else. American Christians do not fear that we will be put to death or imprisoned for our faith, at least not yet, so the symbol stuck to cars and other objects serves to identify the user as a believer in Jesus Christ.
A word of caution for those who are just learning about this symbol. First, one is not a Christian simply by sporting a symbol of a fish on his or her car. One is a Christian  if one has recognized that he or she is a sinner, repented of that sinfulness, and committed his or her life to Jesus Christ. A life lived out for Jesus is a much better witness than a plastic fish on one’s car.
Secondly, be sure to look closely at any fish symbol you noticed in public. There are several parodies and mockeries of it in existence. Evolutionists, pastafarians (a parody religion that pretends to worship pasta), and even Trekkies (avid fans of Star Trek) have molded the Christian fish symbol to represent their interests. Just because you see a fish symbol on someone’s vehicle does not mean they are your spiritual brother or sister in Christ.
The common fish symbol seen on cars, and other places, is a symbol of Christianity. It was initially designed to allow Christians to identify each other while, at the same time, preventing those hostile to Christianity from identifying believers. Today, in America, one can display the symbol without fear of persecution from the government. The Christian fish symbol should be displayed to remind the Christian to be a faithful follower of Jesus Christ, to show other Christians that they are not alone, and to challenge non-believers to consider the claims of Christianity.
Another Reading: 10 Famous Christian Martyrs 
Resources – The Holy Bible, English Standard Version “Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.”
The New International Dictionary of the Christian Church. J. D. Douglas, ed. Zondervan Publishing Co. 1978.