The main thing is that you have to decide how big to buy your tank first! If the tank is not big enough, raising goldfish in summer or dog days may lead to death due to lack of oxygen! It doesn't matter if you have an aerator in your water tank!
You are suitable for raising:
1-2 black butterfly tail or dzi beads (out of the eye) and celestial eyes (avoiding villains). If you like black, black goldfish can only account for one-third to one-half of the total number of goldfish. Too much is bad for your fortune!
2-3 alternating gold plating or lanshou with white and red, (safe and smooth)
2-3 lion heads with gold or yellow and white or red and yellow, (lucky)
2-3 red hats or red tops (life is booming)
1-2 pieces of five-flower gold or extra-eye gold (this kind of gold is easy to raise and beautiful)
You have never raised or fed goldfish before. If the tank is big, I suggest you choose grass goldfish from koi fish or goldfish.
You can mix them freely, and you can ask me if you don't understand!
I hope my answer can help you!