Of course they do! They can't live if they don't! I have 2 goldfishes which live in separate tanks, and theres only 1 oxygen machine,and we only used it on 1 goldfish, and then the other died!! So yes, they do need it!!
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ANOTHER ANSWER
the important thing is that there is oxygen in the water. i achieved this by digging a half metre deep pond in the garden (hoping this is deep enough to not completely freeze in our winters), covering with tarpaulin (you're supposed to have a carpet underlay and overlay to stop the plastic photo-degrading and make it last for years). i filled it with tap water and left it a couple of days to let the fluorine evaporate. then i went to my local pond and got lots of completely submerged plants to oxygenate the water for a week. i also added floating water plants from the pond to provide some cover from sunlight in areas and some marginals with roots in the water to plant round the edges to provide protection and stagnant water for insect larvae which the goldfish feed on. i added lots of pond water-snails to eat dead leaves which have formed a mulch. i bought some shrimp to breed in the pond for food too. i added the goldfish by leaving their bag in the water for an hour before opening it so they could acclimatise to the temperature. one week later and 5 of my 6 baby goldfish look healthy; they have perky sticky-outy fins, swim quickly and are growing much more quickly than i thought they would, their gills are not moving too fast and they are not gulping oxygen from the surface of the water. one looks floppy and lethargic at the bottom of the pond. (aside on my injured fish: i mistakenly poured the fish out of the bag into the pond, leaving one fish trapped and struggling in the plastic in the bag without any water for a second. i think fish injure easily and should have put the opened bag in the water and let the fish swim out. blood-worms from the pet shop have made short work of the dead carcass and my now larger goldfish eat them ravenously, though i really should have quarantined the injured fish. the excess of plants absorbing nitrates and plant cover not allowing much sunlight into the water mean the pond is still clear and i have no algae, though i suppose algae would oxygenate the water too. i find green water unsightly and like to watch the fish.)
yes
Everyone needs a bubble machine.
No. Water is oxygen to them so they need to be in water in the plastic bowl.
Yes, like all pet fish, goldfish need more oxygen than can be provided by just a bowl of water.
Oxygen.
Goldfish filters need to be on all day and night. Goldfish are the messiest fish around so do NOT keep it in a bowl. Besides filters also help provide oxygen.
Yes, a goldfish's respiration requires Oxygen in order to work. Without oxygen, the fish's body could not perform essential bodily functions and would thus cause the fish to die. Oddly enough, if you were to put a goldfish in pure oxygen then it would still die. This is because it's gills need water in order to receive oxygen molecules.
Yes, like all animals, goldfish need oxygen. They get it through their gills from the water they swim in .Air should be provided to an aquarium via a small pump. This helps to remove gasses from the water that might build up and provides oxygen that will dissolve into the water. It also helps keep the tank clean.yes they do
The goldfish will get more oxygen in the day, but at night, they will be competing for oxygen.
Fish need to breath oxygen and they create carbon dioxide. As the oxygen gets tied up in the CO2, there is no longer any oxygen to support the fish and it dies. Plants break down CO2 and create oxygen.
using their gills they obtain oxygen from the top of the water.
Your goldfish may be making bubbles in its tank because it is trying to breathe air from the surface of the water. This behavior is normal for goldfish and helps them get oxygen when the water is low in oxygen levels.