none really i had fan tailed guppies and zebra fish in with my gold fish and he ate there heads. we had to take him back to charlies
other goldfish and mabey som catfish
goldfish mainly
No goldfish would prefer to have a lower temperature than any type of tropical fish, however some goldfish can withstand higher temperature if they are slowly acclimated to it! But in the long run goldfish would be happy with other goldfish and tropical fish with tropical fish... there is a reason you don't see the goldfish with the tropical fish in a good aquatic store.
You can't put tropical fish with each other or they will eat eachother
another gold fish or try asking someone in a pet shop that sells fish maybe they can help
The only fish I know of that is called a celestial is a type of goldfish. If that is the case then most other fancy goldfish would be OK as companions provided the tank is large enough. A single goldfish needs at least 10 gallons of water to live reasonably well.
Betta fish are best as a solitary fish and are not compatible with goldfish.
You need to provide 1 gallon of water per inch of fish. Goldfish get along fine with other goldfish.
None, goldfish are cold water fish, so having a tropical fish as a tank-mate just wouldn't work because tropical fish need to live in warm water.
almost any other type of fish just make sure their bigger than the gold fishes mouth or the goldfish will eat it
it depends on what type of fish.a goldfish has to be in room temperature water.
Koi is a type of fish. Just don't put koi in the pond and it will not be a koi pond.