Help! Angel is going to pop

My fire fish goby died (well actually disappeared) a couple days ago, I have a couple of mushrooms that are turning white and not opening up like they used to and now tonight I find my Angel fish (Coral Beauty) with one eye that looks like it's in a bubble and is going to pop out or just pop - looks nasty. Water parameters seem OK - SG 1.023, Nitrites = 0, Nitrates = 20 ppm (which is not optimal but shouldn't be causing this). I recently added a green leather - is it possible this introduced something into the tank? Any thoughts on what might be wrong with the Angel and what I should do?

 

Might be some kind of parasitic infection. If this is a reef tank, QT the angel and treat there, as the meds might cause harm to corals. In my tank, corals come first, I rather let a fish die than dose anything that might endanger my corals.
Try these links:
http://www.fishjunkies.com/Disorders/gas_bubble_disease.php
http://www.reefs.org/library/article/cripes_kowalski_phipps.html
It might also be pop eye, although I have not experienced this disease in marine fish.

How much light do you have in the tank? They might be dying off due to lack of light. When they turn pale, they are pretty much dying, bleaching. It can also be bad water quality.

I'm sorry, but 20ppm is unacceptable in a reef tank. If you ask a lot of pros on here, they will tell you they keep the 'trates at 0ppm. Anything above 0ppm is a no no in my book. Try lowering the nitrates by adding media and turning up the skimmer to remove organics and proteins in the water. Water change would also be something to consider. When in doubt, do a change! ;D Also, are you testing? How are the phosphates looking?

 

Hmm well...the fire fish...im guessing is just hiding somtimes my guy hides for weeks before i see him...but if there is a bug going around...well then he could have died...sorry

 

Put your angel in a Qt tank and treat with an antiobiotic like sulfa or penicillin. I had a fish that had popeye disease and I was able to save it with triple sulfa. If you act fast you can save its eye too if its not too damaged.

 

I have a coral beauty that had the same eye problem. I quarantined him and treated him with "PraziPro" by aquarium solutions and it worked great and have had no more problems. I don't know how true it is but I was told by someone that because the coral beauty picks at rocks it also picks up bacteria and other stuff from the rock. Whatever the cause, that stuff worked really well. Good luck.