Hi all! 
My aquarium was delivered last week and I finally got everything mostly situated. Still waiting on my new filters to arrive, they shipped today thankfully! I’m currently running my two Fluval 206’s from my 29 gallon which are doing a surprisingly good job keeping parameters in check and the water clear. I’ll be upgrading to two Fluval 407’s with spray bars which will put me around 7.5x total turnover per hour. It will also look a bit better since I didn’t spend a lot of time cleaning and positioning the intakes and outputs since it’s only temporary.

My fish Mama loves her new friends and everyone is getting along great! Can’t wait to get another fish soon.  I’ve been spending a crazy amount of time watching the tank, it’s so relaxing!

I also want to recommend TruVu aquariums to anyone considering a new tank. They have been wonderful to work with and the aquarium and stand they built are so gorgeous!

 

I don't know anything about the genetics of breeding goldfish for colors.  

If one were to breed two yellow (lemon) goldfish, would their offspring be yellow also, or would they come out in different colors?


And what about breeding fish that were both yellow and white like the photo below?


And . . . what about breeding one fish that was pure yellow with a fish that is both yellow and white?

Guidelines are recommendations by experienced goldfish keepers for those of lesser (or no) experience. They are not the only way of keeping goldfish, or even the best, but are our compromise between ideal conditions for goldfish and the space, time, and money limitations of the goldfish hobbyist. Koko’s guidelines are continually reviewed and updated as needed by the moderating team as we gain new information from research and experience.
Tank

Your tank should be large enough to provide at least 20 gallons (76 liters) for each goldfish. This is true for both long-bodied and fancy goldfish. While baby goldfish can do well in a smaller tank short term, they grow very fast, so we recommend starting them in their grown-up tank.  If you provide less than 20 gallons per adult fish, you should increase the amount of water changed to maintain water quality.

The ideal tank for goldfish is shallow with a large surface area. Tall tanks should be avoided if possible.  If you have a shallow tank or a tall one, use the surface area to determine stocking level -- 2 square feet of surface area per goldfish.  We recommend the 40B (40 gallon breeder) for two goldfish since it meets both criteria -- 20 gallons per fish and 2.25 square feet per fish.
 

Filtration

The most common filters for goldfish tanks are HOBs (hang on the back) or canisters. We recommend a HOB filter be rated by the manufacturer as turning over at least 10 times the tank volume per hour. Thus a HOB filter for a 20 gallon (76L) tank should turn over at least 200 gph (760 lph).  If one has multiple HOBs the turnover rates should add up to at least 10x the tank volume per hour.

Canisters have more filter volume, and we recommend they turn over at least 5-7 times the tank volume per hour.

We do not recommend internal filters for goldfish.