With me up and down posting what was wrong, sometimes between this it fell off..
So i have not been able to find it.. i have treated the tank after doing a 60% waterchange, hopefully the tank will recover, im just concerned about the plecs left in it.
The fish didn't look well so R.I.P.
Good that you did a water change.
Are you sure the yellow thing was a parasite.
If so I would try and find it.
Did it look like a leech to you.