Please don't put the goldfish in something without filtration. . . Look back at sweetsuvvyb's post, and read it carefully. The different dietary needs mentioned go for both types of fish, tropicals and goldfish (which are not tropical fish). Tropical fish, generally speaking, require a whole lot more protein in their diets than do goldfish. Goldfish don't have true stomachs and feeding too much protein can bind them up in a hurry. That's why supplemental feedings of veggie flakes, zucchini, green peas, etc. are recommending, to keep the goldfish from getting what is commonly referred to as "swim bladder disease," but is actually a major case of constipation and left unchecked, can kill the fish.
Waste is a major issue with goldfish. The amount of space required to keep a goldfish healthy is related to the wasteload the fish produces and this is not proportionate to its length. The amount of waste produced by a fancy goldfish is proportionate to its weight, which increases roughly with the cube of its length. In other words, a 2 inch oranda produces waste equivalent to eight 1 inch orandas.
On the other hand, feeding only goldfish food to the tetras, rasboras, guppy and white clouds will eventually stunt their growth, if not outright starve them. You shouldn't even mix different types of goldfish. Orandas, moors and celestials have limited vision, and don't see as well as their other fancy cousins, ryunkins, veiltails and fantails. This means if you have those mixed, you have stay vigilant to make sure the first don't slowly starve because they get beaten to the dinner table.
All of the above have not got a snowball's chance to compete in a race to the trough with comets, commons and shubunkins, which are much slimmer and swim much faster. The celestials (or telescope eyes), bless their hearts, shouldn't be mixed with any others, and shouldn't have any sharp objects (including the tips of plastic plant leaves) in their tanks that could puncture those globe eyes.
Sorry to be so long-winded, but I just cringe when I wander into a mega store and see a couple of small goldfish (any variety) mixed in a tropical tank. I usually stand there until the hapless employee goes to get his/her manager, so I can explain why we just don't do that. It's not right for either species of fish.
