Cories with blister outside their gill cover (C. Trileanatus

[thegirlundertherainbow]

I noticed today 2 of my Cories (C. Trileanatus) had a perfectly round, looks like an egg..clear..thing..just outside of their gill cover on the left side. I say two.. I think there were two like this..but I have 9 total, plus 3 C. Elegans, so it's kinda hard at feeding time to count.. At first I thought it was food that went throught the gills..cuz that's where it is..but NO oddly, if it is on more than one fish, and I think it is..it's always on the left side.
Any ideas? Ever picture I take, light reflects off the "thing" making it blend in with the cory's white..
Parasite?
if so, can I get something and mix in a 5 gal bucket and put them in for awhile to get rid of it?

Trying to see if I can get a pic..

[certan]

Could it be just the shine of the operculum under light? (depending on the direction of the light and the position of the fish, the left side in your case)
I hope it is.

[thegirlundertherainbow]

It stuck out about 1/8 of an inch..when the cory was facing me.
It's not as big today. Still trying to get a decent pic..

[thegirlundertherainbow]

not great..this is the hardest thing I've ever tried to photograph. The opacity didn't come through..it came through less clear than it actually was. These were taken last night..it's not this big today.