What is this?

[nickiwit]

My sargassum trigger has a growth under his gill that gets larger each day. Does anyone know what this is? I thought maybe it was a goiter. I have been adding iodine to the tank. I also started feeding a larger variety of food with supplements. This doesn't seem to be helping. Any advice would be appreciated. I have had this fish about 3 years. No new fish added.

Here are some pictures.

http://reefcentral.com/gallery/data/527/62379sargassum1.jpg

http://reefcentral.com/gallery/data/527/62379Trigger.jpg

 

[nickiwit]

Anyone have any advice?

I have the worst luck trying to get any fish disease help on Reef Central.