green neon tetra pale

[Knew tooth is]

One of my green neon tetras is pale and possibly slightly bloated (see fish in center of photo). The tetra has had this appearance for nearly a week, and its condition hasn't changed. It has been swimming fine and eating OK. One difference is that the tetra appears to be territorial or at least aggressive towards other neons when they come around, although the tetra does swim with the other neons. I hadn't previously noticed the aggressive behavior with any of the tetras. The tetra has been in the tank for about 4 months. All of the other tetras appear normal as do other fish in the tank. The water parameters are nitrate 10-20, nitrite 0, ammonia 0, pH 7.8, GH 143 ppm, KH 89.5 ppm. Does this tetra have the dreaded "neon tetra" disease? I've looked on the web for a comparable photo but haven't been able to conclude. Thanks. 

[Colu]

It could be neon tetra disease looking at the picture I would Quarantine the sick fish and treat with aquarium salt 1 table spoon for 2 gallons and maracyn it could bacterial infection and monitor if it is neon tetra disease there are no  treatments available

[Knew tooth is]

Colu- thanks for the advice. This is what I was afraid of. If it were neon tetra disease, is this disease communicable? And, if it were neon tetra disease, what is the chance for survival? Thank you.

[Colu]

It highly infectious it usual spread went other fish cannibaliz dead fish in the tank i would sperate the sick fish they can live along time with neon tetra disease there are no effective   treatment 

[Colu]

From I what I have read the best thing for neon tetra disease is to maintain stable water parameters