When I was keeping fancy goldfish (fantails), I had them in tanks with rainbowfish and kept the pH around 7.6, and the GH about 200ppm. The water temperature dropped to 18C in winter and got to 30C+ in summer.
I fed the fish on goldfish pellets, frozen marine mix (prawn, fish & squid blended up), brineshrimp, daphnia, mysis shrimp, prawn. I also had duckweed on the surface and the fish ate that.
I did a big water change and gravel clean every week. I cleaned the filters once a month.
My tap water was dechlorinated and modified a week before it was used. By modified I added mineral salts (Rift Lake water conditioner) to increase the GH to 200ppm.
I dewormed all my fish when I got them and this usually dealt with gill flukes too.
I fed the fish on goldfish pellets, frozen marine mix (prawn, fish & squid blended up), brineshrimp, daphnia, mysis shrimp, prawn. I also had duckweed on the surface and the fish ate that.
I did a big water change and gravel clean every week. I cleaned the filters once a month.
My tap water was dechlorinated and modified a week before it was used. By modified I added mineral salts (Rift Lake water conditioner) to increase the GH to 200ppm.
I dewormed all my fish when I got them and this usually dealt with gill flukes too.