Posted May 13, 2014
I got my goldfish (Swimmy - creative, I know) for free during a 'kid day' at my local supermarket/department store. My sister received one as well. They were just your basic goldfish, designed as 'filler' fish for aquariums or as feeder fish for other animals.
Swimmy was all gold, and my sister's fishes were varying colors, from yellow and black to gold and white. Swimmy was a hearty fish, and grew quickly - essentially 'choking out' the other fish, and killing them.
Maintenance was simple, and the fish were kept in a standard fishbowl, which was cleaned every third day. The difficulty arose in the content of the water used in the bowl, which caused some fungal growth on the fins. There was a bit of an expense in purchasing appropriate water treatment chemicals to cure this fin fungus.
Eventually Swimmy got too big for his bowl and we awoke one morning (after 4 years) to find him laying on the floor of the kitchen. He had jumped out of the bowl while we were asleep.
So while Swimmy's end with us was less than happy, I would still recommend a common goldfish, especially as a first pet for a younger child. It teaches them the responsibility of owning an animal, but also allows them the happiness of owning their own pet.