Goldfish are peacefull fish and do not normally fight with one another.
Fantail goldfish are a hardy breed, strong swimmers and they compete well for food with the ryukin, shubunkin, comet or common goldfish; making these goldfish breeds good tank mates for your fantail goldfish.
yes
Female Fantail goldfish can not get pregnant they lay/scatter eggs when they are chased by males . So you have nothing to worry about.
The fantail goldfish is asserting it's dominance over the common goldfish. The fantail goldfish has already established in its mind that the whole tank is its territory and will fight any other fish that try to change that. This is normal when adding new fish to an established tank and they will usually continue to fight for a couple more days. During this time make sure to give the fish plenty of food to eat and some place for the common goldfish to hide. If they do not stop fighting after several days than I would recommend moving the common goldfish to its own separate tank of at least 20 gallons. Another reason (though not as likely) is that the common goldfish is a female and the fantail is a male. A male may chase a females rear- this is normal but if he harrasses her- remove her immediately.
it has a short tail
Yes, but slowly.
A fantail goldfish can be any of the goldfish colours which can include any or all of the following white, gold, silver, copper, blue, orange etc etc.
Survival of the fittest
They are both goldfish and so can breed with one another if they are of different sexes.
suma nimo
Became a coluar
Fantail goldfish eggs are adhesive and attach to aquatic vegetation. The eggs are light brown, transparent, and round. They normally hatch within 48 to 72 hours.