What you have probably heard of is "Neon Tetra Disease", or NTD. The name is hopeless. It was first isolated in the species, but can affect many species, not just tetras, certainly Cyprinids, (Barbs, Danios, etc.), can contract it.
It is a parasitic infection by sporozoans. These are cyst forming parasites which develop typically in the muscle. Their growth tends to force the fish out of shape, they become bent or "corrugated" in appearance. It is a contagious condition, and not economically worth treating. In cases where sporozoan parasitism is CERTAIN, the best way forward is euthenasia of the affected fish, and disposal by cremation.
The poor hygiene in many low price fish farms and stockists have made this once rare condition, an everyday experience.