I have a 20g high, planted community tank. About 2 weeks ago, there was a huge nitrate spike causing internal parasites, fin rots, and deaths in my tank. Now, this tank was recently put together so deaths among my new fish was foreseen. I lost two platys before I found that they had an internal parasite (white, stringy poop). I immediately did an AQ salt treatment for 10 days, doing 100% water changes. This seemed to get rid of most of my female betta's fin rot except one. During the salt treatment, I also did 4 paraguard dips everyday for one hour (stopped after I noticed improvement). After the salt treatment, I did a 100% water change, added stresscoat+, prime, and stability. I also added bettafix (halve the dose) at first, but then I read that it could be bad so I did an immediate 75% water change the day after. Now I am not sure what to do at this point because I heard that salt treatment should stop at 10 days and no more. I have a few options but I want people's expertise on this: 1) Take out the female betta and treat with Kanaplex in a separate tank. I heard Kanaplex is a strong medication and I am not quite sure if it is a great idea to expose healthy fish to it. 2) Treat with bettafix with a half the dose in a separate tank. 3) More AQ salt treatment in a separate tank I'm not even sure if separating a female betta from her sorority is the best idea but I really do not want to treat the entire tank with strong medications that they do not need. I also have Metroplex on hand, in case of anything.