Adam Clarke on John 21:6

And ye shall find - The Ethiopic, three copies of the Itala, and St. Cyril, add, They said therefore unto him, we have labored all the night and caught nothing, nevertheless at thy command we will let down the net. This is borrowed from Luk 5:5.

For the multitude of fishes - This was intended as an emblem of the immense number of souls which should be converted to God by their ministry; according to the promise of Christ, Mat 4:19.