Molly (fish)

According to the TARDIS information system as read out loud by the Eighth Doctor, a molly was "a small, fresh-water fish popular in aquariums that has been bred in many colours, especially black". They had dark eyes. The Eighth Doctor read out this information to Molly O'Sullivan when she called his name — "the Doctor" — a "tenth rate stage name". He then proceeded to nickname her "Dark Eyes" after the characteristic eyes of mollies. (AUDIO: Fugitives)