Question

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?
invasive species
introduced species
native species
symbiotic species

Answer 1

introduced species

They were brought into the pond by people and had no known local population. "Invasive" would only apply if they establish, spread and cause harm; "native" and "symbiotic" don't fit.