We have a small goldfish that is having trouble keeping itself upright in our small pond. It’s almost funny until he/she (?) tries to eat and can’t stop from turning upside down when trying to suck up a piece of the food. I can’t help feeling that he/she must be awfully hungry, but this fish is really “fat” relative to its length. Most of the time, he/she just lays on the bottom as if asleep! Any idea what’s happening?
It sounds like your fish has “Dropsy”. This fish disease is generally caused by problems with water quality. Testing the water for nitrite and lowering that levels to 0 should prevent any of your other pond fish from getting the same disease.
A partial water change of 1/3 to 1/2 the pond water is generally needed (may have to be repeated several times over a few days). Stop all feeding of the pond fish until levels return to normal. Add a good beneficial bacteria product to jump start the nitrification cycle of your pond.
Fish with Dropsy can, unfortunately, not usually be saved.