The Georgia Aquarium in Atlanta says some of its otters tested positive for the coronavirus after they showed mild respiratory symptoms.

The Asian small-clawed otters were tested after they had common COVID-19 symptoms, like sneezing, runny noses, mild lethargy and coughing, the aquarium said in a news release Sunday. They are off exhibit and being cared for behind the scenes, where they were already improving and are expected to make a full recovery, the release says.

The aquarium has been following recommended health and safety protocols, but it is suspected the otters may have caught the infection from an asymptomatic staffer. Though animal-to-human transmission is rare, all staff members who’d had contact with the otters have been tested.