A North Carolina aquarium that said it had a pregnant stingray with no male companion now says the fish has a rare reproductive disease.

Thursday’s statement from the Aquarium and Shark Lab in Hendersonville did not say what disease the stingray, Charlotte, has or comment on the status of her pregnancy. The aquarium did not immediately respond to an email from The Associated Press seeking more information.

“Charlotte has developed a rare reproductive disease that has negatively impacted her reproductive system,” the aquarium said. “The findings are truly a sad and unexpected medical development. Our priority is to focus on Charlotte’s health and well being.”

The aquarium in the Blue Ridge Mountains had announced Charlotte’s pregnancy in February, stating that she hadn’t shared a tank with a male of her species in at least eight years. The aquarium said at the time that she was pregnant with as many as four pups and could give birth within two weeks.

The pregnancy was thought to be the result of a type of asexual reproduction called parthenogenesis, in which offspring develop from unfertilized eggs, meaning there is no genetic contribution by a male. The mostly rare phenomenon can occur in some insects, fish, amphibians, birds and reptiles, but not in mammals. Documented examples have included California condors, Komodo dragons and yellow-bellied water snakes.