I have this yellow tank in QT. Ammonia is 0.5, Ph 8. I have a skimmer, UV sterilizer, and filter running. This yellow tank has black fins that seem to come a go. Maybe an indication of stress? I have a few other fish, green chromis and a small clown fish. All of them are eating and show no external signs of stress. Possibly ich? No black spots that I can see. All of the fish have been in this tank for about 3 weeks. Using Red Sea salt and RODI. SG 1.025.