Is The Neon Tetra Decease?

[SMartin]

Hello, is this Neon Tetra Disease? :

I purchased four neons and three were dead within 2 days.
I didn't notice any visible symptoms but they were huddling together in corner and would just show up dead in the mornings.
I had 6 ph at the time and thought it might have been too much ph shock for the neons.

Soon after I noticed the appearance of the remaining neon tetra (as seen in photo) but decided to keep him alive as he was acting normal.
He has been alive for over a month now with much the same appearance.

I am wondering if it could be Neon Tetra Disease or is it just a birth defect?

Maybe I bought some badly bred neons? They were on sale for $1 each.

I also have 3 healthy looking glow-light tetras. If this IS Neon Tetra Disease wouldn't they all be infected too by now?

Tank Info:

ph: 7
nitrate: 10
nitrite: 0
ammonia: 0

Tank size: 35 litre (small)
Fish: 2 clown loaches, 1 otto, 3 glowlight tetras, 1 kuhli loach (all looking healthy).

Thanks!

EDIT: Also Here is some pictures I've found of the disease..

 

[WILDER]

Your tanks severely overstocked.

Clown loaches grow big so need large tanks of 90 gallons.
Also they shouldn't be kept in groups of no less than 3.

None of the fish in your tank should be kept in that tank size.
Research the fish before you buy for adult size, tank size, and compatability.

Its not ntd as that start of as bleaching of the red stripe area.

What the ph of the store to your tank.
Also neons need excellent water quality and mature tanks of 6 months.

Is there a pink patch on the neons tummy.

The fist pic looks like false ntd, which is columnaris.
The second pic is ntd, yellow colour in the blue area.
The third pic is definately ntd.
The 4th pic looks like ntd.