Sorry for double post tried to edit but was not fast enough
I have had success quarantining the fish and using a small syringe or small pipette with 3% Mag sulfate solution (Epsom salt) 1 Tablespoon per 500ml of distilled water...and adding a small amount to their GI for several days (only for fish that just began to stop eating and have white stringy feces). You have to get past their gills though and the process is more tedious with smaller fish so you will need a small sized cannula . You should soak their food in this solution anyways and feed your fish that are still eating for prophylaxis. Remember Metro has poor water solubility so treating the entire tank gets very expensive and its efficacy is well (They are internal parasites)...better to get some Metro Flake from Ken's...this is a great product to keep around and great for your fish that continue to eat because it is ingested and has direct contact.
I have been more unsuccessful with Clout than successful, but many others have had some success. Remember to rule out hyper-aggression, and correctly diagnose the problem before moving forward with treatment...as well as eliminating the source of stress. As stated above...keep your water stable do not poor stuff in it trying to match the lake imho. I have had more success at keeping fish in stable parameters than creating swings of hardness, ph, and other chemistry in my tank. This is all drawn from my own opinions, experiences, and should not be taken as absolute fact.