Best tank for guppy fry ?

I recommend at least a 10 gallon tank (20 long are nice), sponge filter, heater. That's all I use. I clean the tank twice a week really just to get the waste and uneaten food off the bottom. I find that bare bottom tank is easiest to clean with fry. I have some plants that stick to the walls for hiding places and java moss dd over them. I use my desk lamp on a timer for a light. Keep it simple for raising babies. Best of luck!