sinking fish...

Question
i bought 3 golf fish in Aug.  after about a week one of them sank and he looked sick. He would sort of move sometimes but most of the time he would just lay at the bottom and breath.  then eventually died.  This soon happened to all of the other fish one at a time with about a week in between each of them.   I then got a new tank, had petsmart check my water, put new stuff in it that they gave me and said would work, changed the food and got one new black moor. with in 2 weeks the same thing happened, and then i tried one more, and yet again.  so now i have an empty tank and the think is i really love that kind of fish i just cant bear to kill another one because every time it gets sick i get all sad.  Am i just a fish killer or is there something thats making them die that im doing wrong?

Answer
Hello Chloe-

It's hard to tell without knowing your water conditions. Do you remember the numbers PetsMart told you? How big is your tank? For three small or medium sized gold fish, you need to have at least a 20 gallon tank with a good filter (not just a bubbler or an air stone.) They grow big! You also need to remove the tank's heater (if there is one) since goldfish are cool water fish. Goldfish also produce a LOT of waste that can build up very quickly if your tank isn't cycled properly.

Here is a link that explains cycling:
http://fins.actwin.com/mirror/begin-cycling.html

Hope this helps,
Amber Worman