More often simple water changes and ensuring properly fortified foods are used will help clear up common fin rot issues. Using meds on something like this should be a last resort. Instead of a large 25% change, I would suggest 2-3 smaller 15% changes spaced a few days apart. Lowering the DOC
and other pollutants will allow the fish's natural immune system to get the upper hand while it also reduces the available food sources feeding the bacteria...