Goldfish can make excellent pets, but it's never a good idea to release one into the wild when you're ready to relinquish your pet ownership.
Many people might think that releasing a home-grown goldfish into the wild would be bad for the goldfish because it's not used to a wild environment, but the opposite is true. Goldfish are an invasive species, and they'll quickly adapt to their new home and wreak havoc on existing fish.
But how? In more ways than one. These invasive little fish eat almost anything in sight and can grow larger than the size of an American football. Not only can they steal prey from other fish in the water, but they stir up sediment and cause algae blooms that are no good for surrounding wildlife. And if that wasn't bad enough, they can also introduce foreign parasites.
Many irresponsible pet owners dump their goldfish into natural waterways every year, and animal experts are beginning to take notice. It costs thousands of dollars every year to keep invasive goldfish under control. Without such efforts, goldfish could potentially destroy everything and destroy the delicate balance that exists in every ecosystem.
So think carefully before you dump your next goldfish...