Possible Sick Rummy Nose? Please Help!

[gasmask]

Hi.
A few weeks back I got a bunch of 6 Rummy Nose Tetras.
They are all young (a lot smaller than the adults allready in my tank) and all seem very happy and have blended in well with the existing RN's.
The day I got them, I noticed their bodies were all clear except one, who has a kind of white stomach. It kind of looks like he has white food in his belly.
Thinking it may go away soon I (risky) put him in with the rest.

A few weeks have past, his stomach looks the same. He is otherwise healty and happy looking, and it may be nothing.
But an opinion from you guys would be fantastic. Please see the 2 photos below. (not the best pics, but pretty much shows what im talking about)
Cheers!

 

[sangah10]

could it be one of his stomaches have ruptured ? but if it was that wudnt he be dead. :\

 

[WILDER]

Post in the right part of the forum to see if any other members rummy noses look like that.
Does it look like a tumour.