Sorry but I really don't agree with buying a fish for your tank just to have it as a utility fish or part of your clean up crew. I find the best way is to find the underlying source of the problem and fix it there, not just cover it up with a fish.
A pleco or a group of ottos, on top of cleaning up the algae also make nice aquarium fish he wouldn't be using them strictly as a utility that would just be an added bonus.