As far as solutions and/or cures, start small, some kosher salt as I previously suggested. At this point adding meds, especially when you don't even know exactly what if anything you are dealing with, will just further stress your fish.
I don't know where you get some of your info from, but EBJD do not have any problem digesting pellets - unless one is feeding them pellets full of low grade ingredients. What do you think importers/vendors feed their EBJD, crushed powder from unicorn horns? Jeff Rapps fed his commercial catfish crumble, with no issues, when I bought my first EBJD years ago. Pellets aren't an issue, but genetic weaklings among this species is very common, which is why one seldom sees 9-10 adult specimens. Most die before they reach those sizes.
As far as severe stunting, the only thing I see is a slightly enlarged or swollen eye, exophthalmia, which could be due to a number of factors.