Can you post some pictures of these osmocote capsules?
Isn't 12 capsules of the stuff too much to add? How long has this tank been running?
If I was to supplement the substrate with gel caps, I would use 3. (Left, Center, Right)
I can't figure out which one is the gourami. Too early in the morning for me.
Any fish with weird bumps, spots gets removed immediately for observation.
Good luck catching the suspect.