The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It is commonly kept as a pet in indoor aquariums, and is one of the most popular aquarium fish. Goldfish released into the wild have become an invasive pest in parts of North America and Australia. 
"Did you know that goldfish are not only a popular choice for indoor aquariums, but they are also considered to be one of the most well-known and loved species of freshwater fish? However, be cautious when releasing them into the wild as they have been known to become invasive and cause issues in North America and Australia."