A fish can, indeed, swim with an octopus!
This video shows how a manatese can swim underwater with its head stuck to a rock.
The video is posted to YouTube by the manateegirls.com Facebook page.
A manateee can also be seen swimming in the ocean with its mouth open in a video posted on YouTube.
A video on YouTube shows a man in the Philippines trying to swim with his fish while it was still submerged.
The man can be seen trying to move the fish by pulling on it.