help tang not breathing from one gill

[2revup]

my blue tang is not breathing on one side, i can see the gills look fine, just one side is not opening the other is doing all the work, however it dosnt appear that he is stressing that much, breathing appears to be no different from the other tangs..
He has done some erratic swiming more so then normal... Any suggestions

thanks

 

[FOSELONE]

hhmm...mouth to mouth???

 

[Gordonious]

What happened?!?!?! My French Angelfish started doing the same thing, it is only breathing from one gill and very rapidly.