Water changes causes fish to freak out

Question
Hello and thank you for your help. I have a 55 gallon tank with 5 goldfish and 2 sucker fish. We recently moved to a new city, since the move everytime I change the water the fish seem to"freak" out. The swim at a 45 degree angle with no purpose. The usually will remain at the top and will sometimes jump out of the water hitting the lid. Then they fall to bottom and lay there for several minutes. After that will continue doing the above scenario. I have had one goldfish die and one sucker fish also. The rest seem to recover after a awhile. I do have a water softner and thought that maybe this was the problem, I also had one in the old house but this never happened, so I used an outside slickest this time. The results were the same. I don't know why this continues to happen as I am not doing anything different from what I used to in the old house. Can you please help?
Thanks,
Brandon

Answer
Hello,
This is a textbook case of Cl-/Br-/I- Poisoning. Many cities put these ions into the water for taste and sanitation purposes, but they wreak havoc on fish and aquatic life. Your fish recover because the ions eventually diffuse into the air.
"Dechlorinator" is commonly available in pet stores. Just use that regularly with waterchanges and you should be fine.
Your other option is to get a clean 50 gallon drum (plastic)  and store water in there 72 hours prior to a water change with aeration. These will both remove the ions, some people even do both simultaneously.