I noticed tonight my smallest discus (around 3.5") has alittle fin rot. All the other tankmates are fine by the way. I have been consistent doing daily 70% to 80% water changes. This guy is definitely the runt of the group and does get bullied at feeding time from time to time. What can I do to cure this before it gets worse?
Tank is 75 gallons with 7 discus
Ph- 6.8
Ammonia and nitrites are 0 ppm
Nitrates are 5 ppm
Temp is 84 degrees
