Had fasting anything to do with golden trout in Middle Ages?

Question

When I read a short story by Ambrose Bierce, 'Monk and the Hangman's daughter', I found a strange expression as below: >At length we reached the bank of a stream whose silvery waters presented a most refreshing sight. In its crystal depths between the rocks we could see beautiful golden trout as large as the carp in the pond of our monastery at Passau. Even in these wild places Heaven had provided bountifully **for the fasting of the faithful**. I just wondered if they used to eat some golden trout after fasting in those years. Why did Bierce use that expression in the first place?

Answer 1

As far as I can tell, he is merely expressing that "golden trout" is a greater reward "for the fasting of the faithful" than would say, a loaf of bread. It's just some flowery language meant to give a more pleasant visual for the reader than anything else.