Clingfish is used to describe many different species (and genera) of fish. My guess is something in the genus Gobiesox, as they can be found in tropical/subtropical waters and look like the freshwater suckerfish you described. They're intertidal, and are known to move in and out of water (not a good thing for home aquariums). They generally feed on mollusks, crustaceans, and other small inverts.
I have had these in my reef tank in the past with no problems. They would eat by taking small meaty pieces of fish out of my fingers. There ability to swim through open water is pretty limitted.
I have a Carribean cling fish.He is gray with a thin white edge on his dorsal. I fell for him immediately because he reminded me so much of a freshwater Plecostomous. This guy swims right into my hand everytime I put it in the tank. He eats out of my hand and off a spoon. I don't think they get very big, and they are certaily not aggressive. I had some links , but they are no longer working. I remember seeing a beautiful red one on the net.
