Bro, live stock very hard to say one. Swimming ard dont mean it is fine. Sometimes my fish swimmimg ard in the morning only to find it dead at night. Even human can die in their sleep. Take it easy and u will find the hobby more enjoyable.
If u intend to keep fish only, my advise is hypo treatment or seachem copper. These are the only proven methods. I used seachem copper for my tank with good result. Within 3 days u will see the difference. Good luck.
What do u intend to keep? If coral tank, 5 to 10% weekly is better. If fowlr, if load is heavy, change more. For my tank, i change 50% every 2 weeks. Tap water i mix with prime and add salt. Change water on the same day.