Cestria (portrayed by Steffanie Malanga) is an Aquitian that appeared as a final love interest for Billy Cranston. She was first encountered when Billy began to suffer from accelerated aging, during which time Billy travelled to Aquitar to receive treatment. When he was cured, he chose to remain on Aquitar with Cestria rather than return home to Earth, as he had fallen in love with her and thus chose to spend the rest of his life with her. This pairing is somewhat humorous given the fact that Billy once suffered from ichthyophobia.