They took a closer look at the fish and realized they’d discovered a new species: Hoplisoma noxium, or the noxium armored catfish. Several wild-caught Hoplisoma noxium, or noxium armored catfish.

Last October, an invasive species never before seen in North America was discovered in the deep waters of the Port of Stockton, about 92 miles east of San Francisco. No larger than the size of a ...