A family released their pet fish family into a local pond. The fish had no known local population. The impact of the fish on the ecosystem is not yet known. Which term would best define the fish added to the pond?

The fish had no known local population and were brought into the pond by people, so they are an introduced species. “Invasive species” would imply that the fish spread or cause harm, and the question says their impact is not yet known.

AI-written and checked against the verified answer.