Neon Tetra Has Strange Whiteish Growth.

[BOBJOESIM]

Hi,
So i've recently bought a group of ~6 neon tetras for my planted 10 gallon aquarium and I've ran into a few problems as of recently:
1.One of my tetras has already died, possibly from stress, but i tried acclimating them in the aquarium water mixed with the stores for an hour. There weren't any other symptoms/signs.
2. I have this annoying snail problem (small black snails that rarely grow to be more than a cm that just reproduce like hell) and i do not know how to get rid of them. I've washed this aquarium multiple times out along with the plants and it isnt working.
3. One of the rest of my tetras has to whiteish growth (2 days after purchase) and sometimes he swims tilted (head towards gravel, back fin towards surface), and it has appeared overnight. I have attached the photo of it with this subject, and this is the topic i am most concerned about. It doesnt seem like ick (it's localized to a specific part of its body) and I've done a 50% water change 5 days ago. I installed a new ammonia filter as well.

 

[twintanks]

I'm still new to tropicals, but I imagine the infection came with the fish from the supplier, rather than picking it up from your tank, if you've only had them 2 days. If it's a fungus (or even a bacterial infection) these things need time to develop to the visible state; hence the reason for thinking he'd already got it before you bought him. Poor little chap. If this was a goldfish I'd say it was fungus....I don't yet know what fungal infections look like on tetras.

 

[BOBJOESIM]

It's strange though, i haven't seen a sign of it while he was in the store or yesterday, it just popped up...If it is a fungal/bacterial infection, how should I treat it considering that he's with 4 others (although they seem to be staying away from him ever since it showed up), with a minimal amount of stress? Shoud I quarintine him?

 

[BOBJOESIM]

Nevermind, he's on his side and near the surface breathing frantically now. He's probably dead in a couple of hours. Worst thing yet, it seems as if one of my other fish also have it.

 

[BOBJOESIM]

Ok well somehow, two fishes started showing symptoms and died within 6 hours of doing so...this disease is really scaring me. Oh well, I guess I have to hope the rest arent infected.

 

[twintanks]

That's a quickish death rate; on the other hand they are very small fish and can succumb very quickly to an aggressive infection. If you still have 4 live ones and have another container to quarantine them in, you could move them for treatment...then again, if they are your only fish, you could treat them in situ. You'd have to do water changes anyway, eventually.
 
Now, if it's a fungus (and I cant really tell from your picture but it looks rather like one) then it will need a treatment suitable for tetras....I'm assuming that what works for goldfish will also work for tetras, but don't quote me on that, you'd have to check with your fish supplier. If your 4 remaining ones don't have the bug in question, then the treatment won't hurt them anyway.
 
Fungus infection is generally an opportunistic pathogen; it's not so much a fungus as a bacterium or sometimes a protozoan, picking on fish with weak immune systems, stress, and/or damage to the scales or fins. These organisms are readily present in most tanks, as "background" organisms, causing little to no problems for healthy fish.
Your tank......well, I know very little about snails, and I don't know whether they have the capacity to harbour fungus-causing organisms. Thorough washing of plants usually gets rid of most, but I have failed to follow my own advice recently and now have a number of "pond-snails"  in my new tank

  ....I believe potassium permanganate solution (KMnO4) can be used to dunk the plants in, for treatment, before final rinsing in water, prior to tank placement.
 
You might just have been very unlucky with the fish you did buy. They are so small, so delicate. But see if you can find a treatment for them, it's better than doing nothing.