What would a protein skimmer do in a freshwater aquarium

Question

What would a protein skimmer do in a freshwater aquarium

Answer 1

it does nothing for a freshwater aquarium.

Answer 2

Protein skimmers do not function in freshwater aquariums.  

Answer 3

Different skimmers work differently they are not all the same.  Protein skimmers remove microscopic material in water   (uneaten foods that have broken down, wastes (proteins). etc.

They do work on fresh water however most of the time it isn't needed.  

Skimmers are designed to help with the Ammonia and nitrites.  Water changes only can remove the nitrates.

Yes you can use one but it isn't usually needed since fresh water fish waste is a "solid" where as salt water fish waste is a liquid.