Now that you mention it Cerianthus, this fish does seem emaciated. And considering what an appetite angelfish have, it means something is out of sorts...
Just a smear using Q-tip or clean fingertip. It should not take more than a second or two to apply.
At least I diy contraptions as needed basis but this should not be that difficult.
When doing in the net becareful as long dorsal and anal fin get broken/damaged.
Have someone hold the net to a point fish is only partially above water , just enough so holes are above water to apply ointment.
If you see an improvement after day or two, I would just observe until completely healed.
If no improvement or gets worse, try applying again.
With worst cut and gash on fish, they usually healed after one application.
Godd Luck!
BTW, I am very curious as to loss of weight in relation to holes on same area.
Perhaps no relation. Comparison between previous pics and now may provide some answers???
I finally was able to view vid and it seems she is as thin before. Very odd!
Could it be possible that such constant spawning maybe diverting all the energy to breeding?
Out of curiosity, did you ever had any hatchlings/frys from this pair's clutches?
I meant wigglers still on the leaf before becoming free swmming.
Although I could not tell for sure from vid, I am thinking they may be two females if you never saw any hatchlings or eggs fungus up in few days (gone in few days).