No. The temperature variation will kill one or the other. (Too warm for cold water fish, too cold for tropical fish)
No! because tropical fish live in heated water and koi in cold water.
No, goldfish are best with goldfish with the exception of weather (dojo) loaches, bristlenose plecos, and apple/mystery snails.Although goldfish can survive in warmer water temperatures, they are a "cold water" fish and not a tropical fish.
The conditions required are the same as the from came from which is normal cold water, non salt based.
Tropical fish must be mixed with other fish that are well adapted to the same community as the tropical fish are. These would be fish that are non-aggressive, and like basically the same foods, water temperatures, plants and environment.
No! marine fish are salt water fish and tropicals are fresh water fish, this cannot be changed.
Angel fish are semi aggressive fish. They may have a tendancy to pick on the gold fish. Also, angelfish need tropical warm water to survive. Gold fish like cold water. I would not put them together. If the Angel is big enough it will eat your goldfish.
I think that the shark would eat the goldfish probably. I suggest don't try it.
No cos gold fish are cold water fish and star fish are sea water
It's not recommended due to the temperature differences (goldfish is a cold water fish and tropical are, well, tropical), also a goldfish will produce a lot more ammonia which it is slightly more able to resist than most tropical species. But over all it is possible.
No they can not the have to stay in a tank that is at least 70 to 80 degrees all the time. It is the same way with pretty much any tropical fish.
Goldfish are meant to live in cold water, not the warm water in a tropical aquarium. This is a huge reason why goldfish and tropicals shouldn't be in the same tank.
I am not sure of the question but an Freshwater Angelfish is sold as a freshwater tropical fish.