Why 153 fish?
Recently I was asked what the great author on biblical archeology, Giuseppe Ricciotti, had to say about the famous catch of 153 fish mentioned in John 21:11. It would be so easy to digress into all sorts of topics - fish (borh real and symbolic) miracles, numbers - and the mysterious thing called "psephy" - which was an ancient sort of magic/horoscopic/predictive/symbolic thing by which a given word was converted into a number, or vice-versa. (The famous example for this is 666, the "number of the beast" from Rev/Apoc 13:18.) But for today, the feast of the Assumption, I will merely quote Father's words and let it go, since they suffice:
Why this number, 153? Obviously, because when the Apostles counted the catch, as fishermen usally did, they found they had 153. Ancient commentators discovered mysterious mystical meanings in the number, and since their explanations were didactic in purpose there is nothing to be said against them. For example, St. Augustine noticed that 153 is the sum of all the numbers from one to seventeen: 1+2+3+ ... + 17 = 153) and hence it is the sum of the first ten numbers, representing the Decalogue, plus the seven successive numbers, representing the gifts of the Holy Spirit that help men to observe the ten commandments. Others saw in it the conversion of the Gentiles (100) plus that of the Jews (50) plus the belief in the Trinity (3). Such were the mystical meanings the ancients found. Those modern scholars who see nothing but allegory in the fourth Gospel would have another fine opportunity to demonstrate their theiss in this number as they did in the case of the seven husbands of the smaraitan woman and the porticoes of the pool of Bezatha and the brothers of Dives, but they have not done anything about it. Or better, they have perhaps done too much, because so many and such absurd solutions have been proposed that the most recent scholars have concluded, more reasonably, that the number represents a riddle. It is impossible not to discover a riddle when the sensible explanations are rejected.
[Ricciotti, The Life of Christ, 663-4, note on § 636, emphasis added.]
Postscript: I heartily recommend this and the other books by Father Ricciotti - they are excellent, and well worth your time in finding, buying, reading, and re-reading.
A further note: since 153 is the sum of the integers from 1 to 17 - that is, (17*18)/2, it is a "triangular number" - which is yet another bit of symbolism. You can make a perfect triangle if you stack that many beer cans together. Hint, that requires six cases plus another nine cans.