redness

Hello, My discus has redness in the nostril area for the past few days. What should I do? Should I quarantine it? Here is my aquarium water test results : Tds : around 150 Nitrate : 10~25 Nitrite : 0.5 Gh : 4~8 Kh: 0 Ph: lower than 6.4 CL : 0 Water system: Reverse osmosis (RO)

Tank size: ~5 Gal. US pH:7.8 (This is what it has been since I started measuring) ammonia: >0ppm (just the slightest hint of green, not enough to put it at .25, but more than 0) nitrite: 0 ppm nitrate: 40 ppm kH: Unknown gH: Unknown tank temp: 80F Fish Symptoms (include full description...

Hello people,   I'm new to the hobby and have my first tank (cycled and everything) have had fish in for over a month after the cycle and have low levels of ammonia etc and pH is good but have a problem with one fish.   Physical- I recently found that one of my rasbora had an angry red area on...

Okay so I only noticed to day that my black moor has been swimming on it's side and has a huge red patches on it's side. He was in a tank with 4 goldfish and has been living there for the past 3 years, The tank has two filters and a heater set on 22/24 I think Do you have any more questions...