Well just one of them and it wasn't my fault. The aerator thingy on my son's tank was not making bubbles like the one on my daughter's fish tank. I kept checking it and moving it around, but then I would see bubbles coming out so I though all is well. I guess as soon as I closed the lid it would stop working. Poor fish! We had it for just over 24-hours and it's dead. My son was so sweet. I asked him if he wanted to say anything about his fish before its burial (which was a quick flush). He said this little prayer, "Dear God. Take care of my goldfish in heaven. I really liked having you. You were a good swimmer. I'm so sad now." Then he walked out of the room all teared up. I am standing there in tears. What a sweet and sensitive boy I have. On the day he was born I looked at him and told my husband that he had thoughtful eyes. He was going to be such a thoughtful and compassionate child. I told Garrett I would get a new tank tomorrow and some new fish. Daddy said he could have three and he has already named them. Ben (like his first fish), Jerry, and Tom. He has a cute sense of humor too. Wish me luck on the new fish. I don't want to go through this ordeal again. Doesn't it just crush you to see your child so sad. I am going to make sure the aerator works on the new tank.