Sick goldfish in my pond

Question
In our retirement home we have a built pond , with a liner about 10,000 gallons. The pond is about 2 years old. It has a fountain and a filter pump which is the largest available for this size of pond, has a UV light inside and is on 24/7. In the pond we have about 50/60 fish, mainly goldfish and a few comets. Most of the fish seem to be thriving and getting quite large. In the last two weeks I noticed about 3 smaller goldfish, one after another, unable to swim upright , swimming on their sides, and then disappearing (I guess they died and sank to the bottom) Is this an air bladder problem, can I do anything about it in a pond this size, and my biggest worry, is it contagious? I don't know anuyhthing about fish, but I do feed them twice a day, and the water is pretty clear due to the filter.
Any help you can give, would be appreciated.
Thanks.
Frank Downs

Answer
Frank,

It sounds like you got yourself a great pond going there :)

Your Sideways fish is common goldfish because of their body shapes. Dry food eaten quickly swells up in the goldfish's intestine and keeps the fish from controlling its swim bladder properly.

To help, feed the fish pre-soaked or gel-based foods. Green foods are also helpful; peas in particular. I advise peas that have been cooked and removed from there shell. Also, it is not contagous. No worries there :)



Hope that sheds some light
Andy