Each time you change the water in the fish tank, be sure the new water has been tempered. keep your goldfish in a plastic bag, while cleaning and filling is process. after filling with new water, place the unopened plastic bag, containing your goldfish, in the new water. allow 20 minutes for the old and new water to temper together. open plastic bag and allow your goldfish to escape, gradually. dramatic temperature changes, for goldfish, can be unhealthy.this may be the reason your goldfish are lying on the bottom stones of your tank.

Don't ever do a 100% water change, and especially never scrub out the entire tank. You've effectively killed every useful bacteria in the tank. Your tank has gone from being cycled, which means that fish poop converts to less-toxic nitrates quickly, to being "new" meaning that all that fish waste sits around as extremely toxic ammonia. You need to do water changes of 20% every other day for the next three weeks, and check your ammonia, nitrite, and nitrate levels. Your ammonia and nitrite levels should eventually fall to zero.

they have the symptoms of Nitrite Poisoning; when you cleaned out your tank, you effectively brought your tank back to "ground zero" so it is as if you have just set up a new tank for the first time and thus you now need to cycle the tank. you need to buy a water test kit. I use the Jungle brand 6 test Quick Dip strips, which test for Nitrate, Nitrite, Hardness, Chlorine, and PH. I also use the Ammonia Quick Dip strips. All pet stores sell these, just ask for them at the place where you bought the fish and they'll help you find them. The reason for the tests is to make sure that your fish don't die from Nitrite Poisoning aka New Tank Syndrome. Read these two articles to find out what Nitrite Poisoning is and how to prevent it. http://freshaquarium.about.com/cs/disease/p/nitritepoison.htm http://freshaquarium.about.com/cs/biologicalcycle/a/nitrogencycle.htm There is no water treatment or cure for it, all you can do is test the water, and than remove 50% (if test results in stress levels) to 90% (if tests result in danger levels) of the water in the tank, and keep testing and changing water every single day, until the nitrite cycle stabilizes (which can take any where from 3 days to 2 months.) This can be the roughest week or month of your fishes lives, but once the nitrite cycle settles again, you'll only need to do tests and water changes one per week (50% change once each week, and 90% change once per month), or any time the test comes back toxic.