Coral Beauty- is this fin rot?

[KrisTENN]

This is in regards to my Coral Beauty Dwarf Angel. She's been in the tank since its setup about 10 months ago and has always done great until now.

120 gallon tank, not including sump.
1 Foxface
1 starry Blenny
2 clownfish
Coral beauty
1 sandsifter starfish
1 cleaner shrimp

1. How old is this aquarium?
10 months

2. If less than six months old, what is ammonia level?

3. What is SG of this aquarium? How measured?
1.023 using a refractometer, just calibrated.

4. When was the last fish added to this aquarium?
Foxface- added about a month ago. He and the Blenny butt heads a little, but I've never seen him so much as look at the angel. I don't think it would be causing her any stress.

5. Was it quarantined? If so, how? And how long? Was it prophylactically treated? How?
No I guess it just takes once to learn my lesson.

6. If you are using a copper based medication, which one? How often do you measure level? When?
N/A

7. If you are using hyposalinity, how did you calibrate your refractometer?
N/A

8. Please describe in detail, the appearance of the fish? If there is one or more pimples, are they lumpy? What color?
Her body color seems to be normal, but she has extremely frayed top fins. They seem to also have a whitish/faded color to them.

9. Please describe the behavior of the fish as best you can. Is it acting reclusive? Is it always up towards the top of the aquarium? Is it avoiding light? How active is the fish?
Noticed 3-4 days ago that she had been staying at the back of the tank for a few days. Was very difficult to see her due to the dark, non-reflective back of the aquarium. Tonight she finally swam out and that's when I noticed how bad she looks. She's swimming around the tank now, which is an improvement from the past week, but she seems to be swimming on her side more than I recall her ever doing. She doesn't seem to be struggling to swim at all, like she still has some strength.

10. Is the fish eating? What?
No, the fish hasn't been eating for at least the last week. Prior to that, her diet consisted of flake food 1X daily, and frozen food 1X daily. Frozen food used is my sis shrimp, formula two, and a special "dwarf angel" food.

 

[ThRoewer]

This looks pretty bad, especially the white wound on the back.
The fish will definitely need antibiotics as there is for sure a secondary infection going on.
But this looks not like the typical finrot, more like he was in a bad fight that he lost Did any of the other fish attack him?

 

[KrisTENN]

Not that I know of. The cleaner shrimp had been in a different tank, and we moved him to this one about 2 months ago. Up until a week ago, the coral beauty would always rub up against the shrimp and he would clean her. Could it have been she let him do that too much? They were ALWAYS together. The Foxface and clownfish don't bother her. The Blenny is a bit of a bully, but I haven't noticed him messing with her. He mostly likes to go back and forth with the Foxface.

 

[KrisTENN]

Update: after going to a local saltwater fish store, they advised me to use nitrofurazone. I removed her from my DT and she's in a 5 gallon hospital tank. She seems to be acting better, but her tail is definitely worse than yesterday. Hopefully this will do the trick.