Raphael said to Tobiah before he reached his father:
“I am certain that his eyes will be opened.
Smear the fish gall on them.
This medicine will make the cataracts shrink and peel off from his eyes;
then your father will again be able to see the light of day.”
(Tobit 11:5-17)

In church art, the Archangel Raphael is usually pictured holding fish.