losing fish

Question
I have a 700 gal round pond and recently having been losing fish like crazy.  I have taken out 50% of the water, put the conditioner and now added parasite guard and Binox.  Am told to take out 25% of water, re condition and then re treat with meds again.  Have lost about  20 fish out of 32.  How long do I continue this and how will I know when it is safe to add fish again?  Should I have a small aquarium to put new fish in for a couple of weeks before adding them to pond and is there anything I should put into that water?   Thanks so much.  I have put so much time into this pond for the last 5 yrs and am really upset.

Answer
Hey Barbara sorry to hear about your fish, I have all kinds of fish 3 salt water aquariums and a 1400 gallon garden pond. The rule of thumb is about 3-5 gallon per fish. Too many fish and nature will take care of the problem.I had 3 fish in mine and they keep breeding and within 4 years I had so many fish they started dyeing so I built 2 more garden ponds and put the extra in there but there is a limit. When you get to 20 try selling them back to a fish store especially if they are KOI. Its is possible you have a disease which in my experience nothing ever cures it without killing the fish. If you are using some kind of copper to treat the disease after you are done all the water has to be replaced.Feel free to ask me more questions or to add more details. Thanks Eric