Yes, you read it right. I caught the brown on a garden slug.
I've done it a few times over the years - - generally when (as tonight) I ran out of ordinary bait.
Slugs actually make surprisingly decent bait - - they're big enough for the fish to see, light colored and stay on the hook fairly well.
They're kinda like the land-based version of leeches - - which I've heard are a popular bait, but I've never gotten around to trying.
One down sid to using slugs, though, they're a gross slimy - - even by bait standards (sort of a "sticky slimy"), and they ooze an unpleasant orange oil when you hook them.