Question
I put in a pond last fall.  I contains approximately 1500 gal. of water.  I have a waterfall and a skimmer box.  I have 9 fish in the pond varing in size from 3" to 8".  They have recently become listless and staying to themselves.  One fish has died.  The pond temp. is 72 degrees.  I had a problem with brown water but activated carbon took care of that problem.  What should I immediate do first?  I don't want any more dead fish.

Answer
Cliff,

You probably have an outbreak of flukes.  These microscopic "leeches" attack the gills and skin of the fish and make them very susceptible to all kinds of infections.  

Find a pond store near you and get something to treat them.  If you have only Koi, Superverm is the best treatment.  But DO NOT treat any other fish, even common goldfish with Superverm.  It will kill them.  Next best treatments are potassium permanganate, or fluke tabs.

You need to do this quickly.   Also, if you don't have any plants in your pond you can add common non-iodized table salt.  That will also help, but it will kill any plants you have.  In 1500 gallons add forty-five (45) pounds of salt.  I know that sounds like a lot, but that's what will stop the flukes.

Good Luck

John