swordtail's bent spine and neon tetra acting weird

icu2

Hello.

I recently set up a 10 gallon fresh water tank with a water pump (no heater at the time of the set up). I filled it out with tap water, added a little bit of conditioner and let it run for about 72 hours. Then I added 3 danios, 1 swordtail and a snail :). A week later I added 3 fancy guppies - 2 of them died within couple days... The 3rd one is still alive and it seems like he's doing pretty good.
Right after that happened I put a heater that is set on 78F. Same day I added some more fish - 1 swordtail, 2 ghost shripms, 2 fancy guppies and 2 neon tetras. One of the new guppies died next day, the other one is doing great so far.
Right after I added those fish the other day, the body of my first swordtail started to look kind of bent. He still eats good (like a pig I should say)and swims around. There's no spots and discoloration on his body. My concern is the slightly bent spine... Is it possible that he got stressed because I added another swordtail that is little bigger than him? Or is it the water quality?
Next week it will be a month since I set up the tank and I haven't change the water yet. All I did 2-3 times is just adding a little tap water that's been already in a bottle and conditioned. Although it looks very clean, the water was never tested. May be I should mention that I'm planning on getting an air pump as well.
The second sick fish is one of my newly added neon tetra. He was ok until today - now he just stands close to the surface and does not really swim. I've noticed a couple of withe spots on the top of his body, close to the head. They look kind of simetrical. He also looks like he is gasping for air.
Since I'm new at that, I'm not sure what to do and how to treat both my swordtail and neon tetra. I'm sorry I can't include any pictures. I hope everything else helps.

Thank you in advance for your help and advice!

mitcore

ok, the sword tail has a broken back, this is not uncommon in fish, i had a golden gourami with a broken back that lived for mths,
The neon sound like it has either ich or a fungul disease, which can both be treated
the fish swim up the top are going after air, which tells me, that there is one of two thing happening in the tank
1: not enough air flow through the tank
2: your ammonia level is high and you need to do a huge water change,
I call this going top side, and it is always one of the above that does it

Once your tank cycled you should have started weekly water changes, I am also wondering what type of filtering system you are using? and has this filter been cleaned in that time span,

Water condition is not as good as they say it is,
controling your water stats yourself ensures the best tank conditions possible,
I personally stay away from conditioners, I have never seen one yet that is as good as it says it is

let me know how you go
hope this helps

icu2

Thanks for your help.
The water pump (10gal) and the heater (100watts) are by "Aquion". As I mentioned earlier I am getting an air pump as well although I was told today that an air pump is really not that necessary for a 10 gal tank. I kind of doubt that and I'm getting it anyway..
How would I know when my water is cycled? I know should've cycled my tank at the very beginning before adding any fish to it.. But anyways, I have a bunch of beautiful fish here and I really don't wanna loose them..