Many are Ignorant as to This, and Ask for Miracles, Which are Signified Under the Names Of Fishes And Whales
42 Therefore will I speak before You, O Lord, what is true, when ignorant men and infidels (for the initiating and gaining of whom the sacraments of initiation and great works of miracles are necessary, which we believe to be signified under the name of “fishes” and “whales”) undertake that Your servants should be bodily refreshed, or should be otherwise succoured for this present life, although they may be ignorant wherefore this is to be done, and to what end; neither do the former feed the latter, nor the latter the former; for neither do the one perform these things through a holy and right intent, nor do the other rejoice in the gifts of those who behold not as yet the fruit. For on that is the mind fed wherein it is gladdened. And, therefore, fishes and whales are not fed on such food as the earth brings not forth until it had been separated and divided from the bitterness of the waters of the sea.
Source: Confessions (New Advent)