Blue Tang injured. Posted in Reef Forum, but treatment may be better here...

[buzz]

Not sure what did it, but my small blue tang (not even 2 inches long), which has been happy in my tank for over a week now has been assaulted! My wife said he is missing a fin, and is all torn up. He is apparently still swimming around OK, but I am really mad!
Other occupants:
small Yellow Tang (bought from same tank and at same time as Blue. They have gotten along fine)
Tomato Clown (hasn't gone near it when I'm watching)
3 Green Chromis
LMB (harmless)
Leopard Wrasse (maybe...haven't seen him since Saturday)
Serpent Star
Big Red Emerald Crab
small Sally Lightfoot
Assorted hermits and snails (nassarious, turbo, astrea)
2 Lettuce Nudibranch
Spec. Gravity 1.023
pH 8.2
Amm - 0
Nitrite - 0
Nitrate - around 10
Just did a 15g water change last night, using RO and Instant Ocean. Not that the parameters are a factor here, but in case someone asks.
If this Tang is torn up as bad as my wife says he is, should I leave it to try to heal? Can they regenerate a fin that is apparently totally gone? Should he be euthanized?

 

[cope787]

IMO, you should put him in a qt. my girlfriend has a blue tang about 1''. it was all messed up. it scratched itself a lot, but now its better. put the blue tang in a qt for a couple of weeks or so and it will recover. oh yeah how big is your tank?

 

[buzz]

100g. All occupants have had plenty of swimming room, and dart in and out of rocks, etc...tangs included. I have plenty of cavework for them.
Well, I went home at lunch, and took a look at it. It looks like crap.
It's entire left side is chewed up. The fin was basically dug out of it's side, and it has an open wound right below the gill where the fin used to be. He is pretty scratched up too. Somehow, he is managing to swim correctly, and is stable. He is eating too, so he doesn't even really seem stressed about it. Weird.
But he looks awful.
Based on the gouge, and the scratches, I am leaning toward my Emerald crab at this point. I don't know what fish I have that could do that kind of damage. It is extreme. The Blue has been wedging himself in a tight crevice in between 2 rocks at night, and has had to back itself out slowly to free itself. I can only guess that it got itself trapped in there, and the crab had an easy meal.
I will QT it tonight when I get home. Should I medicate the fish? If so, with what? I don't see the fin growing back, as it was gouged out completely, not just bitten down low.

 

[buzz]

Terry? Beth? Anyone?

 

[beth]

You really need to get your little tang out of the tank ASAP! This is the work of one of your other fish. Probably the yellow tang, but it could have also been the clown or even the wrasse.
The harrassment won't stop so you need to think of alternatives for this fish.

 

[buzz]

Thank you very much! I didn't QT him last night because my levels were off in my QT tank and I didn't want to shock it. I will use tank water tonight, and begin treatments as suggested. But I checked on him this morning, and he is no worse off than yesterday. Still able to swim, still eating. Apparently no further aggression last night.
The only reason I didn't primarily suspect the Yellow is that they are always swimming around together. They were in the same tank at the LFS, same bag in transport, and same tank since then. When they are swimming around together, there are no signs of aggression. It is like they are buddies. The blue has also spent some time schooling with my chromis which surprised me. And surprisingly enough, my tomato clown, which is rather large never bothers anything.
The crab is on the large end for an emerald, at around 3 inches in diameter including legs. His body is about 1 inch across. The wounds on the blue tang also include some long scratches, which look like claw marks. (The crab is making a trip back to the LFS as soon as I can catch it. He hangs on to the rock pretty tightly.)
The leopard wrasse has never bothered anything in the tank before, but it's possible I suppose. He disappeared shortly after the tangs were introduced, and I haven't seen it since. It is possible that he comes out at night after lights out, and hides during the day.
I really appreciate the help. I'll let you know how it goes. I've never had to treat wounds like this before.