Issues keeping Angels
 

Every angel I add to my tank seems to develop a strange fin wasting away symptom and eventually die. The fins will start to redden, and eventually start to fray and rot away. I always thought it was something in my tank picking on them until now.

I have tried to treat them, put them in a hospital tank, testing water parameters etc with no success.

My latest is a fairly large Emporer that has started to develop this symptom. As usual eats fine, and is actually in a 150 gallon with no other fish.

Is there anything else someone could point me to as the cause?

Sounds like some kind of fin rot or parasite is living in your system. My Moorish Idol had that and I thought I was going to loose him. He had no bottom fin left, his tail was all ragged looking and he had no "streamer" at all. I just made sure my water was well oxygenized (is that a word?) and fed a good mixture of meaty food, garlic, selcon, and nori. It went away on it's own and he is now beautiful again.
Sorry - not much help. Don't know if a lack of oxygen could cause this but I do know that angels really need a lot of oxygen in the water.

Just wondering, if it's parasitic, would a UV sterilizer help?

I have a UV sterilzer in there. What is strange is it never affects anything but the angel