Sick Neon Tetras?

I have a school of 11 neon tetras in my 29 gallon tank. They've been doing great for the past month and a half but the other day I added in some ghost shrimp and two snails and now there seems to be a problem. One is panting heavily and his red is very pale. Another is just panting.

What could be causing this? Could it just be one sick fish or could I have a bigger problem?

The pale one has passed, the other is very close to death, can barely swim.

Tank has 0 ppm ammonia, 0 ppm nitrite, nitrate is a little over 40 ppm (my kit says 40 is good? How would I lower it further?)

 

A water change should help your nitrates.
What conditioner do you use? Prime helps detoxify ammonia, nitrites, and nitrates.
How long has your tank been cycled?

 

A water change should help your nitrates.
What conditioner do you use? Prime helps detoxify ammonia, nitrites, and nitrates.
How long has your tank been cycled?

Okay I'll do a water change as soon as possible!
I use both Aqueon water conditioner and seachem prime (at different times though because I heard they cancel each other out sometimes)
My tank has been cycled for about 2 1/2 months.

Also, everyone else in the tank seems to be perfectly fine. So far it's just been the two neons

 

Could be just a sick one. Neons don't seem to be as hardy as they used to be.

 

I would just stick with prime and stop using the aqueon water conditioner. Esp because prime does the same thing but better

 

I would just stick with prime and stop using the aqueon water conditioner. Esp because prime does the same thing but better

Thanks for the tip!

 

If your water isn't the problem, what about your tank temperature? My neons don't like it above 75°F. I'd possibly check your heater and make sure it's not fluctuating.