Charlie was celebrated when he turned 22 last month. He had already made it to the Guinness Book of World Records as the oldest living sea otter in captivity and was the second to ever reach that age. Sea otters in the wild typically live around 10 to 14 years.
Charlie was orphaned during the El Nino season of 1997 and then brought to the aquarium in 1998 before it officially opened to the public.
The aquarium is offering fans a chance to pay tribute to him on Sunday, April 28. Visitors that day will be able to fill out a card in Charlie's memory that will hang from the sea otter habitat that day.