Why Domestic Goldfish Can Grow to the Size of a Small Dog When Released Into the Wild

Taylor Shouldice of Animalogic explored why domestic goldfish become feral and can grow to the size of a small dog when released into the wild.

There are a couple of reasons why goldfish get so big when they go feral. The first is the unrestricted access to food that they enjoy in the wild. They can gobble up food all day long, no longer stunted by the measly offering of a few flakes a day. Goldfish are also genetically predisposed to get large. When presented with the right cocktail of protein and fat, they are able to balloon to the size of a skunk.

Shouldice consulted with experts to examine the ecological damage caused by these giant feral fish, the challenges of managing their rapid reproduction, and the importance of responsible pet guardianship in protecting native aquatic ecosystems from this environmental problem.

Releasing goldfish into the wild is considered Unauthorized Stocking and is also illegal in many places! They can grow very large. They can outcompete native fish for resources and habitat. … If you find yourself no longer able to care for your goldfish, consider, instead, giving it away, or even better, don’t buy a fish that can become invasive in our ecosystems. And we need to keep our invasive, not native fish in our tanks and not release them.