Lionhead fancy goldfish problem

Question
Hello,
     i hope all is well.I hope you can help me as i have a problem with my lionhead fancy goldfish.I have kept him for about a month and he is around 3-4 inches long.It swims around fine normally but today i noticed that one of his eyes has popped out slightly.It has swollen up and he doesn't seem to be able to move it very well.He was fine yesterday and i am not sure what may have caused it or what i can do to cure him.Please advise.
Thank you

Answer
Dear Mike,
It sounds like your Lionhead goldfish could have Pop-eye.  Because In most cases it is caused by poor water quality, the cause must be treated first. Please preform 50% water changes everyday. Insuring your replacement water is close or equal to the temperature of your aquarium and that it is treated with a good water conditioner.

~Now you may attempt to treat your Lionhead with a good antibiotic medication. There are many medications out there but I trust Mardel products highly. Mardel's Maracyn 1 and Maracyn II can be combined and should be an effective treatment for your poor little Lionhead. It is possible the Lionhead Goldfish could have simply a swelling due to some injury. Keep in mind many pop-eye fish can recover on their own as long as water quality in maintained in excellent condition at all times. For the most part, even in bad cases, the infected fish will recover just fine and sometimes rather quickly.
On a sad note some fish can lose their eye. But I would imagine this would only be due to failing to provide prompt treatment in the first place. Happily, even fish whom have lost an eye can thrive and live a good life.

I really hope this helps! Feel free to write with anymore concerns, or if you need more info...

Best wishes and best of luck with your Lionhead goldfish!
take care,
Karen~