Poorly Tetra

Hello all,
about a week ago, I noticed a bit of what looked like white fluff on my oldest Neon - which over the last week has grown into a white lump just below his dorsal fin around the size of a pinhead.

He is eating fine, swimming fine etc... but this lump has grown over the last 10days of so.

I pulled him out of the main tank, and isolated him in my makeshift hospital tank and am doing a ~25% water change every couple of days and feeding every 3-4 days.

The main tank I do ~20% water change weekly and feed every 1-2 days.

I have added general tonic initially which didn't sort him, and have also tried four says of salt and high temp (28-29degrees) and a couple of days ago tried putting a dose of fungi stop.

He is around 18months old, so it could be old age, but I don't know how long Neons tend to live.

Water parameters are as follows (tested with a liquid type kit):

pH: 8
Nitrate: 10ppm
Nitrite: 0
Ammonia: 0

I started with the small (now hospital) tank which was up and running for >12months, and have in the last 6 months upgraded to a larger tank, and the poorly neon is the last of the initial batch of 6 neons.

I have attached a picture of the poorly fish if it is of any use... It's not too clear, but the best I can get as he's darting around, and obviously camera shy!

Thanks for any help

Tom

Well after a bit of false hope when the initial white patch cleared up with elevated temperature and salt, the fish is now looking worse

His scales are sticking up, and he is hovering about 4" from the surface, twitching and breathing rapidly.

I'm keeping the water clean, but beginning to lose hope for the poor chap.

If anyone has any suggestions, then I would really like to hear them. From Internet research, Dropsy looks the most like what the little guy is suffering from.

Thanks