I have a little clown pleco living in my sump, I move his piece of wood every day to make sure he's still going under there.
Also in my sump is a poor gimpy goldfish. I've had it for almost a year, and he is still only about 1.5 inches (not including his tail.) He has swim bladder disorder and has the whole time I have had him. He lays on the bottom all day long, but eats, and occasionally will push him self around the bottom, and sometimes up into a flutter. He's really cute, his name is Wobbles, and until he shows signs of stress or some other malady, I think he is doing just fine where he is. I have a lot of potted plants under there, and a piece of driftwood for the clown pleco. I hand feed him by taking him in my hand, and pointing his mouth at the food, and he "YOMP" sucks it up real fast. I love that little guy.