Tobias Tobias was sent to a distant city by his blind father Tobit to collect a debt. While carrying out his errand he was escorted by the Archangel Raphael. A fish tried to devour him in the river Tigris, but the angel told the boy to remove its heart, liver and gall, which would later be used to restore his father's eyesight. Book of Tobit 6: 1-4.
The picture is perhaps a late work.