Take from: The Liturgical Year - Dom Prosper Gueranger, 4th Sunday After Pentecost....

The Evangelists have left us the account of two miraculous fishings made by the Apostles in presence of their divine Lord:—one of these is related by St. Luke, and the Church proposes it to our considerations for this Sunday; the other, with its exquisite symbolism, was put before us by the Beloved Disciple, on Easter Wednesday.

The former of these, which took place while our Lord was still in the days of his mortal life, merely describes that the net was cast into the water just as it served the fisherman’s purpose; that it broke with the multitude of the draught, but no notice is taken, by the Evangelist, as to either the number or kind of the fish; in the second, it is our Risen Lord who tells the fishermen, his disciples, that it is to be on the right side of their boat that the net must be let down; it catches, and without breaking, a hundred and fifty great fishes; these are brought to the shore where Jesus was waiting for them, that he might join them with the mysterious bread and fish that he himself had already got ready for his laborers.

The Fathers are unanimous in the interpretation of these two fishings—they represent the Church; first of all, the Church as she now is, and next, as she is to be in eternity. As she now is, the Church is the multitude, without distinction between good and bad; but afterwards, that is, after the resurrection, the good alone will compose the Church, and their number will be forever fixed. The kingdom of heaven, says our Lord, is like to a net cast into the sea, and gathering together of all kind of fishes; which, when it was filled, they drew out, they chose out the good into vessels, but the bad they cast forth.