FISH. - It is one of the most ancient Christian symbols. In Greek, fish is called ΙΧΘΥC, and the letters composing it form the acrostic ΙΧΘΥC ΧΡΙCΤΟC ΘΕΟΥ ΥΙΟC CΩΤΗΡ, that is, Jesus Christ, Son of God, Savior (Optatus, De schismate Donatistarum, 3, 2: CSEL, 24, p. 68). St. Augustine notes that the roasted fish is a symbol of Christ's Passion (In Johann. Tract., 123: PL 35, 1966). There are many Christian inscriptions with the symbol of the fish; G. B. De Rossi collected a group of them as early as 1855 (Epistola de christianis monumentis ΙΧΘΥN exhibentibus, in Spicilegium Solesmense, 3 [1855], p. 573 ff.).
The texts relating to the symbol of the fish were collected in a study by H. Achelis (Das Symbol des Fisches und die Fischdenkmäler der römischen Katakomben, Marburg 1888); but the most important work on the subject, both as regards the literary sources and the analysis of the monuments, was carried out by F. J. Dölger (ΙΧΘΥC Das Fischsymbol in frühchristlicher Zeit, I, Münster 1928, II and III, ibid. 1922; IV, ibid. 1927; V, ibid. 1932-40).
Abercius recalls the fish from a very great and pure spring, which the chaste virgin takes and offers to her friends to eat every day. In the first part of the poem inserted in the inscription of Pectorius, besides the acrostic ΙΧΘΥC, we read: divine offspring of the heavenly ΙΧΘΥC, which is eaten with eagerness; and Pectorius commends himself to all his dear ones who are in the peace of the ΙΧΘΥC. The word was scratched onto the plaster in a mausoleum discovered beneath the basilica of St. Sebastian, introducing into it also the letter T (the sign of the Cross; G. Mancini, Scavi sotto la basilica di S. Sebastiano sull'Appia Antica, in Notizie degli Scavi, 1923, pp. 3-79). In an inscription coming from the Vatican it is said: ΙΧΘΥC ΖΩΝΤΩΝ, that is, fish of the living, which gives life (G. Marchi, Monumenti delle parti primitive, Rome 1844, p. 70). The entire word also occurs in the inscriptions of Postumius Eutherion (Dölger, op. cit., I, fig. 11), of Eutychianus (loc. cit., I, fig. 13), of Colonus (loc. cit., pl. I, no. 103), of Cecilia Placidina (O. Marucchi, Monumenti del Museo cristiano Pio-Lateranense, Milan 1910, pl. 51, 13), of Modena, where the fish is also represented and the word fish is written out in full (G. B. De Rossi, Roma sotterranea, II, Rome 1867, p. 333); of Callistus, etc. (found in Priscilla, in Domitilla, in Praetextatus, in Pamphilus; G. Wilpert, La Croce nelle catacombe, in N. Bull. arch. crist., 8 [1902], p. 10 and pl. 6, 3).
Tertullian affirms that we Christians are little fishes, born in the water, after the likeness of our great fish Jesus Christ, and that only by remaining in the water (that is, in the grace of Baptism) are we saved. This explains the frequency of ancient Christian epitaphs with fish facing toward the loaves and even more toward the anchor; with the anchor and the Good Shepherd in the epitaph of the sarcophagus of Livia Primitiva (G. Wilpert, Principienfragen der christ. Archäologie, Freiburg im Br. 1889, pl. 1, 1). A Greek inscription from the cemetery of Priscilla, placed by Claudius Philotas for his sweetest brother Theodore, ends with the wish that we may live in God, and then a fish is represented, that is, in Jesus Christ, Son of God, Savior (G. B. De Rossi in Bull. Arch. crist., 5th series, 3 [1892], p. 14). In the cemetery of Callistus, in a cubiculum of the end of the 2nd century, two fish are painted with two baskets containing loaves and a cup of wine before them (Wilpert, Pitture, pp. 265-66 and pls. 27, 1 and 28). In the same cemetery, in cubicula A3 and A, above a table, the bread and the fish are represented (loc. cit., pl. 41, 1). In A2 and A3, above a table, the bread and the fish are represented (loc. cit., pp. 267-68 and pls. 38 and 41, 1). The feeding of the crowds by the lake of Tiberias (Jn 21:1 ff.) with loaves and fish is also in the same cubiculum, where before seven men two dishes with two fish are placed (loc. cit., p. 267 and pl. 41, 3); likewise in cubiculum A2 (loc. cit., pp. 267-68, pl. 27, 2); and in cubicula A5 and A6 (loc. cit., pp. 268-69, pls. 41, 4 and 15, 2). Clement of Alexandria recommends to the faithful that they have the allegorical figure of the fish engraved on their rings (Paedagog., 3, 11).