Every Goldfish I put in my pond keeps dying-7 in 3 days died

Question
I was wondering if someone could help me out in getting my goldfish to live in my pond. my pond is 10ft x 15ft and deepest part is approximately 2-2 1/2 ft deep. just got it set up again 1 week ago 6/7/07 used Pondcare Algaecide and some kind of liquid to establish bacteria in the pond. my total gallons of water is 1500gals. i put dechlorinator in it suitable for 1500 gal i have 2 fountains in the pond and a cascade moving water in the pond. i also have 2 filters, one that sits in the pond and another bio filter that sits outside the pond returning filtered water back into the pond. i had 2 parrots feather, 2 water lillies, a cannas, 1 umbrella palm and 1 iris in there when i added my fish each time i added fish they stayed at the top and seemed to to sucking air from the top of the water and they would not eat, one died within 4 hours and the others died overnight sometime i have a test kit for pH nitrites nitrates water hardness and alkalinity which are all in the appropriate ranges, i recently added 6 bunches of anacharis, 1 water lettuce, 3 water hyacinths, and some small duckweed just wondering if you could tell me what could be the cause of every fish dying that i add to my pond and if its lack of oxygen how do i raise the oxygen level?  Thanks Sheri

Answer
Sheri,

Sounds like your pond is just fine.  Where are you buying your fish?  I imagine you are getting sick fish.  Change sources for your fish.  

With your description of your pond, the plants and everything, there is no reason for you to be losing fish.  Very often the fish from local dealers are not completely healthy.  

Most fish problems begin with parasites.  And this is where it becomes difficult.  A population of fish can become resistant to parasites and live just fine infected with them.  You may buy fish and all but one die from parasites and the last one does just fine, but is still infected.  Now, you buy new fish from a new, clean source and put them in the pond without treating the pond.  The parasites move from the infected fish onto all your new fish and they all die.  So now you think something is wrong with the new fish, when in reality it is the one you already had that is the culprit.

Hope this helps,

John