In early Christianity the acronym of the phrase, “Jesus Christ Son of God the Savior, is Ichtus, ΙΧΘΥΣ. It is a symbol of the early Christians who were under persecution to hide their identity from their enemies, seen in the catacombs and on the graves of the martyrs.
The most frequent use of the fish is as a symbol of Christ. This is because the five Greek letters forming the word “fish” are the initial letters of the five words: “Jesus Christ God’s Son Savior” (ιχθυς) (George Ferguson, Signs and Symbols in Christian Art, with illustrations from Paintings of the Renaissance, Oxford University Press, New York, 1961)
This is the first meaning of “fish” as they represent Christ being the source of life in the water. In the Talmud the Messiah is named δαγ (in Hebrew: דג) which is translated “fish.” In the early NT, the Messiah is characterized as the “Living Water” (Nomides, Η Ζωοδοο χος Πηγη, ΤΥΠΟΙΣ ΚΕΦΑΛΙΔΟΥ ΙΣΤΑΝΠΟΥΑ ΔΑΛΑΤΑ ΜΠΑΛΟΥΚ ΠΑΖΑΡ ΚΟΥΡΣΟΥΝΑΟΣ ΧΑΝ, Istanbul, 1937, 39).
Gregory the Theologian describes “fish” as a symbol of Christ in the following poetic way: “Christ received the human element and became a fish as all mortal people (Homily 24). Christ accepted to be descended on earth into the waters of the human race and willingly was caught in the nets of death” (Ibid., 46). Origen metaphorically represents Christ as the fish and says, “the fish is the symbol of humanity (Homily 13, #10)” (Ibid. 42). Also, the symbol of the fish is understood to represent the Eucharist, the food of the faithful, Christ who gives Himself to us in spiritual form (Ibid.). Nomides see a connection between the spring and the sacrament of baptism. Christ was baptized in the water from which the fish come. If the spring represents the Virgin Mary, then the fish represent Christ (Ibid., 43). Again, the fish can represent the Eucharist as the heavenly fish come from the immortal spring. The soul of the receiver of the Eucharist is “decorated with rich wisdom” (Ibid. 44).
It is significant to note that the pool with these special fish gives rise to a popular saying that describes the “Theotokos of the Fish.” The associated shrine, therefore, took its name from the Turkish word, Βαλουκλη’ a name that became associated with the shrine about the 18th century. “Baluk” in Turkish is translated “fish” therefore giving the area its eventual name translated “fish” therefore giving the area its eventual name Baloukli (Ibid., 46). For the pool with the fish we have the following legend: before the fall of Constantinople in 1453 AD, a monk was one day frying fish north of the city near the shrine and another monk was traveling from the city to the shrine. At the time, the city was undergoing a series of enemy attacks. The traveling monk said to the monk frying the fish, “the city is surely going to fall.” And the monk frying fish said, “I will believe this when the fish I am frying become alive again.” Miraculously the fish humped out of the fry pan into the water and started to swim. And so the legend began that from that day up to now the fish are black on one side and red on the other side. Even the visitor today can see the pool with the black and red fish (Ibid., 46, as recorded in ΣΚΑΡΛΑΤΟΥ ΒΥΖΑΝΤΟΥ Η Κων Vol 10, 338). (Virginia M. Kimball, Liturgical Illuminations: Discovering Received Tradition in the Eastern Orthros of Feasts of the Theotokos [Bloomington, Ind.: 2010], 463-65)