Tank Size : 2 gallons with LED light and water stone with pump
Betta type: Crown tailed betta (from Petco)
1st Fish: Crown tailed Betta, 2 gallon 360 degree tank with air stone, 2 fake plants and gravel
I filled the tank with tap water and then treated it with the drops provided with the tank. The water treated for about 30 hours before i introduced the fish to its new home. I did the introduction process where the fish could get used to the temperature and then let it go. I dropped a few betta pellets in the water and then went off to bed. When i woke up, the fish was dead and at the bottom of the tank. Our apartment got down to about 68 degrees so I assumed that the temp got too low and that contributed to the death of the fish.
2nd fish: Crown tailed Betta, 2 gallon 360 degree tank with air stone, 2 fake plants, gravel, water heater made for 2 gallon tank, aquarium salt, and Spring water from wal-mart
I boiled water and cleaned the gravel and tank and the rest of the items in the tank. I then put everything back together and then added the Spring water. I submerged the water heater and waited for the light to turn green so that the water was optimum temp (78-80) degrees. I added a pinch of aquarium salt, and 2 drops of some water treatment. I put the fish in a bag with the original water it came in and let the bag sit in the tank for about 30 minutes before letting the fish go in the water (I made sure NOT to let any of the old water from the store to get into the tank water). I dropped a few betta pellets in the water, and let the fish go. The fish lasted through the night and all day, but when i got home this evening, it was floating in the water DEAD.
WHAT AM I DOING WRONG?!?!?! PLEASE HELP!!!