Neon Tetra With White Spot On Tail

One of my tetras has a white spot on his tail, it kinda looks a little lumpy. (see attached pic, the tetra in the middle). This happened to one of my tetras a month or so ago and he stopped eating and got worse so I put him out of his misery This one is still eating but I would like to save him if possible.

1. Water parameters. (ammonia, nitrate, nitrite, PH, temp', Hardness etc)
28deg, 0ppm ammonia, ph 7.0

2. A full description of the fishes symptoms.
See above

3. How often you do water changes and how much.
20% every week

4. Any chemicals and treatments you add to the water.
I added some melafix to see if it would help. Also added stress coat when moving the fish in (see below)

5. What tank mates are in the tank.
Tanks has 2 clown loaches, 1 pleco, 1 dwarf gourami, 6 danios and 6 neon tetras

6. Tank size.
96L

7. Finally Have you recently added any new fish?
I recently transferred all my fish from a 40L tank to the 96L which was fishless cycled and then had the danios added

I would issolate the fish to be sure.
http/freshaquarium.about.com/cs/disease/p/neondisease.htm

I had ntd and it started at the tail end.

Ok, I've isloated the affected fish in one of those floating breeding tanks in the 96L, will that be safe to prevent the disease spreading? According to that article, the disease is spread by the fish picking at each other.

Should I continue to use melafix/other treatment in the hopes that it is not NTD and just wait it out?

I hope it's not ntd as it awful can wipe a full tank out, would rather it be in a issolation tank of its own, and add a bacterial med to see if you can try and save it, as you can get false ntd as well, but i wouldn' risk leaving the fish in the tank, good luck.

Well I have isolated the fish in a seperate tank, am still treating with melafix but it does not seem to be helping. Should I be trying other meds?

The fish is breathing quite rapidly now, perhaps because he is all alone? *shrug*

What are the water stats in the issolation tank in ammonia,nitrite,nitrate,and ph, if he's heavy breathing not sounding to good i'm afraid, a med could finish him off.

ph 7, 0ppm ammonia, 0-0.025ppm nitrite (hard to tell)