regular water changes/kill

Question
Hi Jaymie,  I have two fish tanks on 29 gals and one 55.  I've changing a small amout in both every week.  The same amount in each tank.  And the last change to my smaller 29 gal tank was on its 6th. week of change and it was a sunday and all the fish died on the following tuesday.  They were covered in a white film like a coating and when I removed the bodies it would flake like dried skin.  Like they were burned.  This has happened several times to me and I love my fish and don't want to have anymore die.  I try to keep them very clean but it still doesn't seem to work.  What am I doing or not doing right or wrong.  Its very frustrating. Any addvise would be so helpfull.  I've asked my favorite pet store who are fish smart but they don't know.  I'm lost.  Never had this problem with fish when I was younger.  I have gold fish and Koi, love them.  Hope you can advise.  Thank you.

                                          Camille

Answer
Camille,

What are your water perimeters? Goldfish are very messy and produce a lot of waste. Make sure you are doing weekly water changes of at least 25%. I am thinking your ammonia and/or nitrites are very high in the tank. I do not know how many fish are in the tanks but one goldfish needs a minimum tank size of 20 gallons and 10 to 15 gallons for every added fish. Also, make sure you are using a water conditioner every time you add fresh water.Let me know what the readings are for ammonia and nitrite.