Periodic Loud Breathing?!?!?

[Gerraldo225]

So over the last couple weeks i've noticed that my Brazillian Rainbow will periodically have a few highly audible breathes (Almost wheeze like i guess). It only seems to happen ever few minutes when he's in his tank(sometimes 10+ mins) and far more often when being handled (20-30 seconds) My immediate first thought was respiratory infection but none of the other "common" symptoms are apperent (eg. Open mouth breathing, fluid discharge from mouth or nostrils, lack of appetite,swollen or bloated body, ect...) So now i'm completely confussed. He's been isolated from that rest of the collection until i have some sort of better idea as to whats going on. Any and all help/input would be much appreciated!!!