If your goldfish is struggling to go down to the bottom of the tank it has a swim bladder problem. There are those who advise a slow raising (up to 80F) and then lowering (down to 55F) of the temperature of the water over about two days for this problem. There are also commercially available "cure alls" that pet shops will happily recommend and sell you. In over 50 years of fish keeping I have yet to see either the temperature manipulation or any of the expensive medications work and fix a swim bladder problem. In my experience the fish will eventually die so I would euthanase it.
you cant
You can use clean tap water for your goldfish, but not dirty or used water.
Take it to the vet
drown it then flush it down the toilet
That is a disease cure it
Because goldfish cant breathe on buses :)
Yes. goldfish breathe water so if a goldfish is out of water it cant breathe so it will suffocate
You cant.
Yes. I put my goldfish in water strait out of the sink. We have a well so I dont know about city water, but I know that you can put well water strait out of the sink. Hope this helps.
yes, goldfish can get traumatized. if the are scared enough, they might get sick or even jump out of their tank if their isn't a lid on it.
you cant
cant