(x-post) HELP! Naso Tang in serious trouble!

[kgerbus]

My wife came home this evening to find our Naso Tang on the bottom of the tank barely breathing. He is very sluggish and is not eating. On his left side there is a bulge. There are no obvious signs of infection.

Any suggestions would be appreciated, thanks!

 

[kgerbus]

He is now lying on his side. Things have gone from bad to worse.

 

[kgerbus]

Bad news, he died last night. However, I would like to figure out what happened. I have had him for about 6 months. The guy I got him from had him for about 3 years. I checked salinity, nitrite, pH, ammonia. All were within acceptable levels. We have noticed that he has not been eating well over the last week.

Thank you for any suggestions!