SOMEDAY I will have a spectacular pond (when I am settled) and until then I am going to become an expert. So surely there will be a series of random questions from me for a few years to come lol. Does the 20 gal. per fish rule of thumb still stand for koi and commons/comets in a pond? I figured just out of common sense you should give them more then that in a pond. How much gallonage per fish do most of you give you outdoor biguns? how many gal. in your ponds and why? (trying to get an idea of how big and how many fish (mainly koi) I will want).

A general rule of thumb that I've been told for koi from an expert was minimum 1,000 gallon pond, allowing 300 gallons per each koi in the pond. So if your pond was 1,000 gallons you could only have 3 koi.
I think it is only around 30 gallons each for the pond goldies.
Be careful if you keep both, they can hybridize.
Hope that helps.
Mary

the koi need 250 gallons ask sandy
common/comets goldfish 20 gallons

I would definetely give your goldfish more room in a pond - mine have somewhat around 30-40 gl per fish, depending on their size and breed. Ranchu need less than a comet or a shubunkin, since they naturally do not grow as large. Pond fish are generally hardier than tank fish, and its nice to watch them from above as well. I think you are gonna love a pond once you get it all set and done. Do you want to plant your pond?