my neon tetra
 

i have 3 blue l-f danios, 4 zebra danios, and 4 neon tetras. one of my tetras have been kind of colorless lately around the midsection, and it seems to come and go, one day its looking sick but still active, and the next its chasing the others around and looks like its having fun. the other fish look normal and are not sick, and only one death in the 3-4 months that i have had it. advice?

This could be a number of things and is something I would pay close attention to. My first thought would be stress.... another thought would be the beginnings of neon tetra disease. If you notice any "white blotches" that stay... you may want to consider moving that fish to a quarrantine tank. Neon tetra disease is highly contageous, but if you can get the infected fish out of the tank soon enough, it is possible to save the others.

Is it possible for you to get pictures to post? Best would be pics of the loss of color...
Also, what size tank is this and how many fish are in it? What are the water params for ammonia, nitrite, nitrate, pH? Water quality can affect the fish in such ways, and usually the weakest fish is the first to show signs.

Another thing to try is to pick up some more Neon Tetras; 4 is a bit small for a shoal. I'd pick up 3-5 more to make them feel more comfortable. This could help out the one that's been colorless, since that is a common symptom of when they don't feel comfortable.

i have a 20 gal high, and i havent tested yet for all the poisonous stuff, but im goin to at the latest this weekend

In a 20 high you won't want to add anymore neons, that would be overstocking the tank.

Yeah I didn't notice it was a 20 high, it would be pushing it to get more, depending on the maintenance schedule and filtration and what not. A lot of those fish should be in larger groups, and in a larger tank.

As much as I said not to add more, I do still agree with this. Neons don't do well in a small tank unless its a species only and enough of the neons are together. In a group of less than 10, they tend to die off one at a time, and usually for no apparent reason. With their schooling instincts, they stress more if there aren't enough. Stress weakens the immune system. Weaker fish without proper conditions (their large group) don't have much of a chance.
However, I won't say its impossible to raise neons in small groups, because I've done it. I had 1 neon that lived with my guppies and mollys for 5 yrs. He was the only neon. The average life span of a healthy neon is about 4 yrs. Time, attention to needs and details, and patience can go a long way.