Dead Fish Please Help!!!

[Danegerous101]

So I am new to this how taking care of fish thing as you will learn. So the first thing that you need to know is that I got my first fish a couple of days ago at a fair that I went to. We needed a tank for it to stay in so I went to the store to get a filter and some gravel and a 10 gallon tank. I came back with 5 more fish a filter gravel and some decorations for the tank. The tank that we are using is a 40 gallon tank. But the catch is that it used to be my lizard cage that passed away a couple of weeks ago. Not knowing that you are not supposed to use any reptile cages for an aquarium we used it anyway. We filled it with water and got the filter going and put the fish that were in the bags in the tank to get the same temperature as the tank. Later we went to the store to get a different filter because the one we got was for a 10 to 30 gallon tank. We got a new filter and a heater and 5 more fish. So at that time we had 2 Neon Tetra, 1 Fantail Goldfish, 2 dalmatian mollies (a male and a female), 2 Orange Swordtails, 2 Green Swordtails, 1 Algae Eater, and the Fish Feeder Goldfish that I got at the fair. Later that day one of the Neon Tetras was dead on the floor of the tank. We went back to Pet Supplies Plus and got it replaced for another Neon Tetra. When We got homethe other Neon Tetra was on the floor of the tank died and we just flushed it down the toilet. Basically on the third day of allthis in the morning I noticed that the water was extremely foggy so foggy that I could barely see any fish at the back of the tank. So that day we went to the store to get a water check and everything came back fine. Later that day the water slowly started to get less foggy. Around 5:00pmI went to a different fish store and got 3 Mini Tetras. After we were done at that store we went to Petsmart and got a male and a female Mickey Mouse Platy. Nowtoday a couple hours after I woke up the female Green Swordtail was in the top left corner dead. We went to the store withthe fish and another water sample to see if anything changed. The water still tested perfect. So while we were at the store we got the Green Swordtail replaced. I got home put the bag with the GreenSwordtail in the tank waited about a half hour before putting it in and it did fine. About 2 hours after that the male Green Swordtail who had a tail a bigger than its body. I don't know what is going on I really just need some advice and help onwhat I should do.

 

[Thatg1r1]

They're probably dying because you introduced so many fish at once and didn't cycle your tank

 

[atlas101]

As the post above states, your tank is not cycled. Have a read through this which will explain the nitrogen cycle:

http://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/

You would be best to return as many fish to the store as possible as it will reduce the amount of water changes you are going to have to do.

The un-cycled tank is likely the cause of your fish deaths, however it is also possible that with so many additions from a couple of different sources that one of them was carrying an illness of some sort to complicate things further for you.

I would try to return as many as possible and read the above link as you are now going through a 'fish-in cycle' which is not ideal but you can minimise the losses with big water changes and following the advice other members have posted.