Yellow tang/ help or opinions needed

[gqlmao]

Hey, its been a while since I have posted on canreef. I have a problem right now... I've had my yellow tang for around a good 5 years now. Around 2 days ago he started fighting aggressively with my bigger blue tang. The blue tang has also been in my tank for a few years. It has been peaceful till now.

The problem is that the yellow tang is damaged, his 2 dorsal fins on the side are swollen and the area around it looks pretty serious (red and pale white). He has not eaten for 2 days and swims in the same area. Water parameters are fine none of my other fishes seem stressed and my tank is 100 gallons so size isnt really an issue consider he is pretty small.

Should I try different types of food?, move him down to my 20 gallon sump? (I don't have an extra tank available) Wait it out for a few more days? If he is not recovering, I think I will have to see to it that he gets a new home.

Any help or advice would be great!

Thanks,

Stanley,