Plecostoumus has turned white

Question
Our Plecostoumus (12 inches and at least 10 years old) has turned white - why? We recently added some feeder gold fish (given to us) and suspect they carried something into the tank. We are removing and replacing water now and replacing the charcoal. We also added some "Cycle - beneficial bacteria and removes ammonia / nitrate levels). Hopefully this will work but any additional suggestions? Thanks...

Answer
The pleco might be stressed out. Does he look like someone sprinkled salt on him or is his color just white? You might what to put some aquarium salt into the tank. You would only put the salt in once. If you want to add more salt you have to take water out and put new water in as salt doesn't filter out.