is a condition that typically does not require QT. The fish is not diseased or ridden with parasites. Normally, improving water and environmental conditions and ensuring that it is getting proper nutrition does the job over time. I've never heard of HLLE
killing a fish quickly, like Ich or MV can do, but leaving the causal factor in place will continue the deterioration of the fish, due to no improvements.
In this case...give the fish a place to feel safe, even if it means buying some pieces of PVC
like you would do in a QT. rock would be best, but maybe expense is a concern? Not sure. Ideally, get it in a proper size aquarium as well. I would add vitamin supplement and maybe throw garlic in as well. couldn't hurt. I'd be willing to bet that would work.