fish swimming upside down

Question
Our black goldfish started swimming upside down. Do you know what do  do and what is the cause? Also the other black fish's eye is like popped out! Can you help me!

Answer
Alright so the pop eye is a disease called Pop Eye. It is serious but treatable with Penicillin or amoxicillin.
Now swimming upside down is Swim Bladder disease. This can be caused by a number of things:
Deformed Bladder
Cancer or Tuberculosis(symptoms-hollow bellied, pale, show skin ulcers and frayed fins, and loss of appetite. Yellowish or darker nodules may appear on the body or eyes)
Poor nutrition
Serious Bacterial or Parasitic infection
Constipation
Chilling or rapid fluctuations in temperature

If it's a deformed Bladder best to put the fish out of it's misery.
If it's Cancer or Tubercluosis, best to destroy the fish.
If it's Poor Nutrition, change the diet to something more nutritious.
If it's a bacterial infection, try some antibiotics such as Maracyn from Mardel Labs which can be found in PetsMart. It contains a variety of antibiotics that should help
If it's a Parasitic infecction, you could try some Jungle Labs Ick Guard. It treats all sorts of Protozan Parasites and is found at Paws Up Pet Supply
If it's constipation, just change the diet until the little guy is normal again.
If it's temperature change, just get the temperature to stay the same.

While trying to determine which one it is, give the fish some live food for roughage it may help.
If it is none of these things, best to detroy the fish.