Hooray! Nice work everyone! I'm so thrilled at the great advice I've read on this thread. You guys are fabulous! What a happy ending!
black_sun, I first have to step up on the soapbox for a second to mention that goldfish are an extremely poor source of nutrition for any and all large predatory fish. Most feeders are raised in huge batches in disease- and parasite-ridden tanks, so they bring in bugs, especially intestinal worms, that will be passed on to the fish that eat them. Secondly, they contain high levels of thiaminase, a chemical that can cause a Vitamin B imbalance and cause serious malnutrition in whatever fish eats them. Finally, goldfish are a very fatty fish and are a poor source of protein.
Now that I've said that, your comet is gorgeous! As Kashta mentioned, the colors may continue to change in your fish for up to three or even four years. You'll see the most changes within the first year, of course, but be aware that you may end up with a pure white or pure orange comet!
120 gallon is an excellent home for your comet and new shub, Bruiser. Be sure to cycle the tank and filter properly (though with other tanks already established, I'm sure you're already set on that part).
The foods mentioned are excellent brands and you'll be fine with any one of them. Remember that goldfish are carp and hence they are omnivorous. So a varied diet is key. Vegetables like cucumber and zucchini, greens like romaine lettuce and live food like brine shrimp, earthworms, or bloodworms are all great options.
And black_sun, in reference to those "big" comets you mentioned, with a 120 gallon tank and good food you should see your two babies grow to 6 inches within their first year! Young goldfish can grow incredibly fast.
Best of luck with them!
