Comet Goldfish

[Goldfishkeeper204]

Can you keep comet goldfish with fancy goldfish?

[Lady Hobbs]

Comets get a foot long and should be in ponds.

[FreshwaterFishGuy]

Can you keep comet goldfish with fancy goldfish?

Some people are able to keep them together successfully but it is not recommended. Comets will out compete the Fancies for food. I have also heard of some cases with Comets nipping at Fancies, and like what Lady Hobbs said, Comets get rather large (12+ inches). I have 3 Common Goldfish (Similar to Comets), one is 14 inches and the other two are over 10 inches. They are in a 75 gallon aquarium and they are past due to be moved into a larger aquarium. As soon as I move they will be put into my 180 gal. (currently in storage).

[madagascariensis]

Think about it. Comets are very close to the wild form of goldfish. They are fast with good senses and grow huge. putting them with a cripple-bodied clumsy-finned variant that has great difficulties to even swim or see food(thanks to their huge wens or deformed eyes)
will starve out the fancy goldfish in most cases. While I do not think that comets or common goldfish will nip at their fancy counterparts out of aggression, It would not be surprising if curiosity makes them nip and the wens or bubble eyes of their mutant bethren.

[Fishguy2727]

I wouldn't mix them. I think in a large tank (at least 125 gallons) well maintained tank (nitrate under 20ppm) they are fine.