Without pictures I would guess that the peppered catfish is probably a corydoras catfish. They don't eat algae but they do a great job of cleaning up all the crud on the ground level of the tank (leftover food, etc.).

If you post a picture of your "algae eater" or link to one that looks like it I'm sure that someone here could identify it for you! Without an id it's hard to say what it might eat...