My tank is 2.5 gallons (I know it is a little small for 3 platys but it was all I could afford) , and it has been up for 2 days now. I haven't tested the water, and it isn't cycled. I have a Mickey Mouse, a red platy, and a sunset fire wag something (sorry I don't remember!)
No I don't have a heater, but I tested it about an hour ago and it was about 78 degrees Fahrenheit.
Yes I have a filter too, and turn it off to feed them