A three inch might be 1year old will it depends on the fish what kind of fish.
no. i have had two big comet goldfish with my, little 2 inch fish, and they never ate him.
Goldfish may take 2-3 years to reach sexual maturity.
3 years. There are no "goldfish" years like there are dog years.
A one human year old goldfish, is eighteen goldfish years old.
You need to provide 1 gallon of water per inch of fish. Goldfish get along fine with other goldfish.
Although the goldfish are very small and it may be tempting to put many goldfish in a tank that large, you have to resist these urges if you want your fish to be happy and healthy. Keep in mind that goldfish grow very large: 6-8 inches for the fancies, 6-12 inches for the more common ones. The rule of thumb "one inch of fish per gallon" just does not work with goldfish. A more accurate measurement of goldfish per gallon would be " for each inch of goldfish allow 3-4 gallons of water". Hope this helps- and remember though the fish are small now, they will soon grow very large and beautiful.
You cannot mix goldfish and bettas. Personalities aside, Goldfish are coldwater fish and Bettas are tropical. I have also heard that once the goldfish get bigger, which they will fast, they will eat the bettas David's answer:Yes, they be each other if you put the goldfish in first.(Note: The betta might nip the goldfish's fins)
If the goldfish are small enough to be swallowed then in all probability that is what will happen.
It depends how big they are if they are still small yes and as long as they are not 3 inch's or more yes.
For twenty small (1-1.5 inch) Goldfish you should have something like a 30 gallon aquarium.
If it is as old as a goldfish that can, it can.
Given warm water (60F) good food and plenty of room to grow and swim in, a goldfish can reach 3 inches+ in 12 months from hatching. In good conditions to go from 1" to 2" would be around 3 months.