Oscar is a Memn, which are a species of highly intelligent Cnidaria from Sestina Colony. He serves as a Navigator aboard the Fast Attack Corvette Fighting Mongoose, where he resides in a large fish-tank on Deck 6.

Memn are highly intelligent and telepathic, but lack technology, so they offer their services as navigators in return for the opportunity to explore the universe.

His favorite foods are fish and eels.

For a time, Oscar made a pet of a decapus the crew acquired at Nocturne colony. One day, the decapus disappeared. No one knows what happened to it.