Fin Rot?

[Hal 9000]

So this is my Royal Gramma. Over the past few weeks his caudal fin has started to disappear. I've seen no aggression from any tank mates but he does spend a lot of time in the rocks which made me think maybe he was getting it rubbed off there. The fin disappeared in strips following the lines in the fin. Now he only has a nub. Today I noticed that one of his pectoral fins is gone (mostly) and his dorsal fin is starting to recede up to the purple/yellow line. He's still eating but spending more and more time in his little hole basically only comes out when I walk up to the tank.

I've looked online and the only thing that looks possible is fin rot but there has been no visible growth on the fins and no fuzziness. Any ideas?

 

[twilliard]

@Humblefish may have a good thought on this!

 

[Humblefish]

Unless you have a crab or some other critter chewing on his fin, odds are he has a lingering bacterial infection. Most of the time a fish's natural immune system is capable of handling this, but sometimes the immune system needs a helping hand via antibiotics. So, I would QT him and dose a broad spectrum antibiotic such as Kanaplex or Furan-2. If you can't find those, there are other options listed here (just look for ones that treat fin/tail rot): http://www.americanaquariumproducts.com/AquariumMedication2.html

If you can't QT, you have two "reef safe" options:

1. Soak Kanaplex in fish food, using Seachem Focus to bind the medication and prevent it from leaching out. Also run carbon as an insurance policy.
2. Soak vitamin supplements (exs. Selcon, Zoecon, Vita-chem) in fish food in an attempt to further boost the immune system to deal with this. No binding is required with this option, as vitamins are not harmful to corals/inverts.

However, neither is going to be as effective as dosing antibiotics directly into the water column so it can be absorbed by the fish's skin.