My engineer goby

Sorry I am no help on what to do.
what kind of tang do you have that is that aggressive?

 

I know that I have heard of people treating things like this but I think it would depend greatly on the size of the gash. I would check foster.and smith and see if you can find a treatment that works for your system.

 

There is a product called "bio bandage". It is similar to the liquid bandages you can get for pp except made specifcally for aqaurium use, however its not a permanant thing and doesnt stay on long term. Its a liquid with antibiotic in it that you "paint" onto the affected area. You may have to do this one to two times a day.

I think fosters may have it....perhaps you can google it and find out who does.

Also, you may try an oral approach as well...there is a product called "gel tek" . Its a somewhat thick liqiud substance that has anitbiotic in it, you soak your food in it (if your fish will eat flake or pellet this will absorb alot more of the meds than your frozen so i would try that first), the food absorbs the meds and then you feed to your fish. This way you are getting the meds right INSIDE your fish so that it can work more effectively and more quickly. For example if you rub an anitbiotic on your skin (topically) your body will absorb it to a degree but it wont get to the source problem as quickly and there fore it may not be completely effective, now if you take an oral anitbiotic, your whole body absorbs the meds and distributes it where you treat the wound from the inside out. You may choose to treat both orally and topically for better overall treatment.
The gel tek comes in different antibiotic form....you may want to read up on what each particular antibiotic treats.

You may have to google search this product,i am not sure if fosters still sells it.

I have used both products with a high success rate.I have a reef and nothing seemed to be adversely affected by the antibiotics. I think it is because you are not dosing the whole tank and there is not enough present to do harm. Plus the small amount that may leach from uneaten food is more than likely taken out by your carbon and water changes.

I hope this helps, goodluck with him.

 

PS.
He may be stressed out in the tub and may not want to eat while in there. Also, added stress could worsen situation- lowering immune system leaving wound more vulnerable for infection.
However if your tang inflicted this wound, you may have problems if you add him back and will have to watch them. If your tang is aggressive you could rearange a few things in the tank upseting your tangs territory and therefore he will have to re-establish it, causing him to be more accepting of the other fish and lessen aggression.

 

biobandage 1+
Where is the gash and how large is it? You can always sedate him in a 5 gal bucket with methleyene blue and subsequently stitch him, I've done so on fish as small as 2"
Petland used to carry biobandage, but it's expensive, and they may have discontinued it. They also don't carry metronidazole anymore....lame!

 

It's always surprising what these little guys will go through. I have a melenurus wrasse that was left behind in a tank when I moved into my 75 (I've moved him again into my 120 since that move) I didn't realize that he slept in the sand bed, my 46 had a 4" sand bed and I had moved all the fish and rock and equipment over into the new tank and there was just 4" of water covering the sand left in the 46. I figured he was up in the rocks some place and he had been moved into the 75, but I was worried about him. 18 hours later, I come home from a little walmart shopping and there he was lay a top the sand bed in just a cm of frigid water. I thought he was dead and I lost it! Then I looked closely and saw that he was actually still breathing, I FREAKED OUT and grabbed him and chucked him a 75. He's my favorite fat fish! Now going on 5 years old!

 

If the tang continues to be aggressive, you can also pull him out and put him in a hospital tank / tub...to let him de-acclimate to the main tank...then introduce him after several days or a week. He will then be the "new" guy in the tank.