I have a heater in the tank that will heat up to 15 gallon tank between 76 and 78 degrees. I also have a couple aponogeton plants in the tank as well.
Is this a pre-set heater or does it have a dial on it that you can set the temperature? Do you have a thermometer in the tank, and if so, what temp does it read? Pre-set heaters can overheat the water.I have a heater in the tank that will heat up to 15 gallon tank between 76 and 78 degrees. I also have a couple aponogeton plants in the tank as well.
So I then bought 8 gold fish for her. they died all but 2.
I cycle the water in the 5 gallon tank maybe once a week.
I am thinking that before the fish get to the size where they need to actually be in a larger tank , I will have had the time to find and purchase one and get it set up, correctly.
That's NOT cycling! You are doing water changes. Cycling means to allow the tank to develop the beneficial bacteria. I suggest you do research on cycling, maintaining a tank and fish compatibility before buying any more fish.