You are thinking of four-line pictus catfish aka Pimelodus blochii that gets to about a foot. Pictus catfish aka Pimelodus pictus gets to only 5".
You'd need at least 5-6 to see some activity from them, otherwise they'd hide too much.
Other candidates are, as you said, hoplo cats, cories, and plecos. Some Doradids, like Trachydoras, don't hide. They essentially behave like cory.
You can filter Cat-eLog on Planet Catfish by size and browse through it.