Instead of getting another fish to control your algae you could instead find the source of what’s causing the algae and stop that? Most of the times it’s over feeding, a lighting issue, or both. If you wish to go that route then we can help you figure out what’s causing it.
As for fish, ottos are small enough that they *might* go unnoticed or at least not be worth the effort to eat.
Nerite snails are good algae eaters as well.