spot treating

Hoping for some feedback on my Achilles. Seeing spots and some rock rubbing on occasion. Other fish seem clear. Seems to be eating well and active. Any thought on what to focus on?

For the record, there is no "cure" for algae as it's not a disease. That's the only reason the word "cure" is in the title. :) Now for HOW to spot-treat algae! (More about "why" after the how...) Fill a small syringe with 1-2 mL of regular hydrogen peroxide Shut off all flow and wait for the...