I deleted your duplicate thread, it's only necessary to start one thread for an issue.
It would be helpful to the other members to know that you lost one yesterday also.
Is this one showing the same symptoms as the one you lost?
I wonder if it's
neon tetra disease (parasitic)or False Neon tetra disease (bacterial).
They have the same symptoms and the only way to really tell the difference is FNT will respond to anti bacterial meds.
Unfortunatly NTD is highly contageous and usually won't respond to meds.
Sounds like you might have gotten a bad batch. How do the others look?
Can you post a pic?