To my knowledge there are no reefs right outside Sandusky Bay. At the Lake mouth of Sandusky Bay (from the Lake end of the channel breakwall entrance) there is a small one just NW of the breakwall, it has a bouy. Forget what it's called. Otherwise, the only shallow water is along the shoreline west and east. To find a shoal or reef, you have to go to the SE corner of Kelleys Island.

Catfish are just about everywhere in the Western Basin, but during the day rocky areas are generally better. Put any kind of live bait down along the bottom and you'll catch them, along with drum (Sheephead) and whatever else happens to be there. Good 'ole nightcrawler on a weight forward spinner or a worm harness works fine (and will also catch walleye). I've had some poor walleye days when after we gave up on them, and just wanted some action, we let the Erie Dearies and worm harnesses drop down to the bottom and we always caught some sheeps and cats. Or a few days when I took a few non-fisherfolks out to just catch fish for fun, I'd head to an area like what was already mentioned in another post here, toss a nightcrwler on a hook with a sinker down along the bottom, and drift. No problem catching sheephead and catfish.

And yes, the entire Sandusky Bay is a hotspot for shore and boat catfishing.