Previous Questions

I think my fish has a problem with its swimbladder

The swim bladder is a small organ inside the fish that can fill up with air or deflate, allowing the fish to move around in the water column more easily. The swim bladder is quite prone to infection, which can cause bloating, disorientated swimming, and involuntary floating or sinking. Alternatively, the gut of fish may have trapped air, caused by constipation or by an infection. 

✔  You should stop feeding for a day or two, and check the water quality using King British 6 in 1 Water Test Strips
✔  Add a salt tonic, such as King British Revitaliser Tonic, to aid osmosis.
✔  Use a treatment specifically designed for this problem, such as King British Swim Bladder Control
✔  Goldfish will often take in air when feeding at the water surface. To avoid this, feed a sinking food, such as King British Goldfish Sinking Pellets

Gut and swim bladder problems are notoriously common in fancy goldfish, which have been over-bred to create their unusual shapes. In some cases, this has adversely affected the structure of the swim bladder.