A baby dolphin born in April at the National Harbor died on Saturday.
The dolphin calf showed signs of sickness on Friday. The aquarium staff and veterinarians worked to save the ocean mammal, without success.
“Staff worked tirelessly to save her and we are devastated by the loss," said Sue Hunter, director of animal programs at the aquarium to WBAL. "This has been an extremely sad and difficult week."
The dolphin's sibling, born on the same day, died on Thursday.
In the wild and in captivity, a third of dolphin calves do not survive their first year of life. An autopsy will be conducted to determine the cause of death, which was not immediately clear this weekend.
The aquarium suspended dolphin shows on Sunday.