My blue tang which has been in my tank for about 4 months has a rear fin that looks like it is deteriating. I started noticing this a couple days ago and it seems as it is getting worse. At first it looked as if something was stuck to it like little hairs. I just did a water change and a couple of days after the water change (catalina water) my koran angel fish died. His color had been fading and finally it happened. Now I see this on my tang. His color is also fading a little. I just fed my fish frozen Spirulina brine shrimp/mysis mix and my tang ate like normal.
My parameters are all 0 except trates are around 30 (high I know but always have been)
My tank is about 7 months old. I have added nothing to the tank within the past 2 months except some snails.
Also in the water change I added amquel, novaqua and kent aquarium essentials. I have always added these at the same time as water changes.
Sorry for the bad pic all i got is a camera phone.