Join Date: Dec 2011
Location: Very far away from you!
Goldfish do not "need" friends.
It is the breeding season and goldfish are clearly going to be interested in mating.
Because your goldfish likes a mirror doesn't mean you need a friend.
Your tank is too small for another fish, anyway. If your fish is a fantail then it will NOT have any trouble "competing" for food anyway. If you have a Black Moor or Telescope Eye or Celestial Eye then it WILL have trouble eating and finding food because its vision will be impaired.
I have a Pearlscale and a Black Moor in the same tank.... They are female and male, and the only reason they find companionship in each other is to mate. They mate every morning (more like the male attempts to mate with the female) and when that is over with they ignore each other and act like the other is part of the scenery.
If you have a Fantail and insist on another fish, upgrade your tank to 30 gallons or more. Ryukins tend to be very aggressive so I would keep them singly or not at all. Comets and Common goldfish aren't very good matches for a Fantail though they are similar in body shape, because the former are more aggressive and play rough.
Good tankmates for a Fantail would be Black Moor, Pearlscale, Oranda, or another Fantail. Any aggressive fish should not be kept with the Fantail. But if you insist on a large-eyes fish, be sure that it receives extra food as the Fantail will be quicker at spotting food, and will eat most of it before the large-eyes fish even realizes that food is around.
7 bettas, 2 goldfish, 50+ (accidental) snails, 2 parakeets, 1 dog, 2 cats
Rest in peace Butch, greatest dog ever, Omelette the Veiltail, and Chipita the Veiltail