Hey there, Ive been a discus owner for close to a year now, initially having no problem with them in the slightest. However in the last 2-3 months I have lost 5 of my 7 discus. The tank is 260 Litres, I do weekly water changes and test the water specs to make sure everything is in order. Each second water change I use RO water and clean the canister filter every two months. None of the water specs are overly worrying, the most recent being PH: 6.5, ammonia: 0.25, nitrite: 0, nitrate:5, GH:4, KH: 1 and water temperature sits at 27 degrees. Not sure if this is relevant or not but the light runs for 8 hours a day and the tank isnt anywhere near direct sunlight. The only symptom the fish have shown of being unwell is lack of eating, I feed morning and night a combination of bloodworm and Thera A however they mostly only pick at the food at night. I have treated with Promthyasul incase of parasites and there is no evidence of tapeworm infection. The plant life in the tank also looks a little dull and droopy, not sure if that's relevant or not. Can someone please let me know if there is any reason I could be missing as to why my fish are dying? Thanks, Grace.