Most starships that have a “Cetacean Ops” segment carry either bottlenose dolphins or beluga whales, (actually a very large dolphin). Both of these species require a marine environment and eat an enormous amount, which would make them very uncomfortable on a small ship like the Trouble. Instead, Hiuw and Fred are La Plata River Dolphins, a much smaller species which is at home in both rivers and estuaries, and is far more able to handle variations in temperature and salinity than either of the usual cetaceans.

Their role on the Trouble is unclear as yet, but they do keep Chip company, and are enjoyed by other members of the crew.