Bubble of fluid on leaf fish?

[melissa_johns]

right above the nose of my leaf fish it looks like he has a large bubble of water. I can actually see through this bubble. I have seen this once before but then it went away..any ideas what this is? He is and African Spotted leaf fish and is 3 inches long, dark green and black. All my tank parameters are great. I did notice this though as I was netting all the fish to move my tank. Is it something that happened from stress? The otehr leaf fish in the ank all look great and so does my black ghost, who I think would show symptoms of stress before everybody else
thanks

 

[Pyramid_Party]

Do you got a pic?

 

[Lupin]

Air bubble disease. Try to increase surface movements to avoid too much saturation of oxygen. It usually goes away though.