The Epic of Siegfried
"We of Asgaard never forget," said he.
He turned his face toward the Rhineland and the magic shoes bore him aloft to the place where he knew Andvari lived with the elves who guarded the greatest hoard of treasure known in the mid-world. He scanned with careful eyes the mountainside, the deep rocky caves, and the dark gorge through which the River Rhine rushed, at its very start no wider than a meadow brook. But in the dim moonlight not a living being could he see, save one lazy salmon swimming in the quiet eddies of the stream. Anyone but Loki would have lost all hope of finding the dwarf king Andvari there, at least before the dawn of day, but his wits were quick and his eyes were very sharp.
"One salmon brought us into this trouble, and another shall help us out of it!" he cried. He unfolded the magic net and cast it into the stream. The cunning fish tried hard to avoid being caught in its meshes, but dart every which way, the skillfully woven cords drew themselves around him and held him fast. Loki pulled the net up out of the water and grasped the helpless fish in his right hand. Lo! as he held the struggling creature high in the air it was no longer a fish, but indeed, the sly dwarf-king Andvari.
"King of the Elves," cried Loki, "your cunning has not saved you. On your life, tell me where your hidden treasure lies!"
The wise dwarf knew whom it was that held him as in a vise and he answered frankly, for it was his only hope of escape. "Turn over the stone upon which you stand. Beneath it, you'll find the treasure you seek."
Loki put his shoulder to the rock and pushed with all his might. Suddenly it turned over as if by magic. Underneath was a wondrous chamber of walls that shone brighter than the sun, and on the floor lay a treasure of gold and glittering gemstones such as no man had ever seen. Loki, in great haste, seized upon the hoard and placed it in the magic net he had borrowed from the Ocean-queen.