From oceans all over the world at great depth.
The longest bony fish in the world is the Giant Oarfish (Regalecus glesne), also known as the King of Herrings. The longest ever recorded was 17 m (56 ft) long, longer even than the confirmed record for the whale shark but not as much as some unconfirmed reports of that same fish.
They are known mostly from dead or dying individuals who make their way to the surface for some reason or end up on beaches, sometimes after storms. Because of this and the way they look, it's thought that Oarfish are the root of many sea monster sightings.
They also eat plankton, which looks like a lot of work to me!
More on the Oarfish.