I have read through posts and am a bit confused on the topic of fin rot. I have a Fancy guppy that seems to be experiencing this on his tail. When stocking the tank we ended up with a couple bullies that were definitely stressing everyone out. We have since removed the culprits and everyone gets along well now. Tank specifics: 7 male guppies 3 emerald green Cory’s 0 ammonia 0 nitrite 10 nitrate Running for about 2.5 months now 20 gallon long with a 30 gallon filter My confusion now is if this is fin rot, will regular water changes and having removed the bullies remedy the situation? Or do I need to treat with some type of medication?