Dwarf Puffer, damaged lip?

[Bittersweet]

Hi,

one of my dwarf pea puffers has stopped eating and has something wrong with or near his lip, hes also breathing heavily now, below are pictures, please could someone help to identify what could be wrong and a possible solution?

I have isolated him in a small tupperware in case its infectious.



TIA

Bitter

 

[OrionGirl]

I can't really tell what's wrong from the pictures. What do you normally feed? Tankmates?