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!