You can take the fish out of the sewer, but you can't take the....ew. Throw it back.

A "giant mudcat" caught by Naegli. It did start singing, but it had a really filthy mouth.
(screengrab via Kyle TheFishWhisperer)

Not many fishermen get full profiles written about them in non-fishing magazines and papers, let alone Texas Monthly and the Houston Chronicle, let alone at the age of 17. But not every fisherman is a 21st Century pioneer like Kyle Naegli of Katy, TX, or as he's known online, "Kyle TheFishWhisperer." Kyle's whispered fish in all sorts of original ways—for example, using remote-controlled toy boats to fish on a pond—but he's best known for bringing the bounties of the local sewer system to the Web's attention.

Sources: Kyle TheFishWhisperer | Houston Chronicle | Texas Monthly