Thank you sooo muchFin rot is gradual, tail drop syndrome is when part or the whole tail completely drops off the Aro at the base all at one go. Why this happens and under what kind of conditions and how come only some Aros suddenly suffer from this not common but very odd condition is quite the enigma. The good news is the tail will very likely grow back, the bad news is most of the time it will never grow back to its past glory.
Salt, no feeding and maintaining good water quality seems to work without need for further medication. Patience is needed for the regrowth period.
After reading this it gave me such a relief!