Neon Tetra Disease Question

[brry]

Okay, so I was able to figure out my tertras have neon tetra disease. They have slowly lost their color and developed tumor/cysts.

What's weird is even the cardinal has it. He has gone completely white. But it's controversial whether or not they are really immune or not.

It's taken a very long time for them to get sick with this, so I think I'm dealing with the real NTD not the false kind, which kills them off in a matter of days.

They've been swimming around over a month like this, pale and colorless, but they are still eating, not hiding or even acting sick. Their color comes back when I turn the light on them for a few hours. Then totally drains again when I turn the light back off.

So. What do I do about my tank now? I have a gourami and a loach in there with them. It doesn't spread to them, does it?

Also, I suppose from this I can't put any new tetras in there when these go, as it's floating around the tank now.

And what about my filter? Do I have to throw my filter out with all the good bacteria? I'm at a loss at what to do now.

What is this I've heard about a UV filter that's supposedly capable of killing the spores?

I don't know how they got it bc they don't eat live food, but I have a funny feeling about some dried bloodworms I was feeding them a while back.

 

[brry]

FALSE ALARM

Turns out I don't have NTD or even FNTD in my tank - what I DID have in my tank, however, was too much aquarium salt. I had misread the directions, and added it as if my fish were sick.

I did a 50% water change, and my tetra's color came back instantly. It was amazing.

For anyone who has pale, fading, tetras - they are sensitive to salt. Being so tiny, and all. It might not be Neon Tetra Disease.

I was puzzling over how this could have happened. Because they don't get live food. And I buy them from a reputable LFS.

 

[brry]

Well, crap. They turned bright colored for several minutes, then turned pale again. Nearly clear.

What's going on?

They seem to be reacting to the overhead lamp. When the lamp is on they are their normal color, but when I turn it back off again they turn pale. None of them are swimming sideways or laying on the bottom or anything. They are all still eating.

I am not the only one who has noticed this problem:

I just bought a school of neon tetra. When I turned off the over-head lamp they got pale but as soon as i turned it back on they went back to there normal color.

Oh. Huh.

They have a physiological response to darkness that causes it. It is likely an adaptation that makes them less visible to predators at night when they are less active and "sleeping"

Is this the explanation?