Agree, we need to know more here. Tank size, and do you have an algae issue now, or is this just preventative?
I can offer a few general observations while we're waiting. First, considering all the species of fish that may/will actually eat algae, none of them will eat all species/types of algae. Most are specialized. And many get large, meaning 5-6 inches (12-15 cm) and up and some have specific requirements respecting numbers (shoaling species need a group) and some have sometimes rough dispositions.
This is why we need to know the "algae" you are after. If just generally, that is one thing, but if you have or are worried about a specific "problem" algae like black brush/beard, that is a very different issue. Generally speaking, no fish should ever be acquired solely to deal with any issue/problem such as algae; all things considered, they are usually more trouble than benefit. But if you have a species that you actually like and want as a fish, and it happens to benefit in another way like eating some types of algae, that's OK. Though sometimes such fish have specialized diets and that has to be considered long-term.
