Is your tank a minimum of 50 gallons? Goldfish get big fast and require a large tank. They do not grow to their environment, like a lot of people think. Goldfish are messy, and they are pretty fragile. If your tank is 50 gallons and you want goldfish I suggest 2 or maybe 3. They will be happy with that size.

Let us know what size your tank is and I can make some good suggestions. I have had African Cichlids for years and I love them. For me they are easier than goldfish.

BTW, having a fresh water tropical tank isn’t harder than having a non-heated tank. All my tanks have heaters, even my betta tank.

Do you know about ammonia poisoning and cycling the tank? I can help you with all that if you need help.