With the continued popularity of pet aquaculture and concurrent demands for advances in veterinary medicine of fish species, a need exists for a reliable, safe, and environmentally noncontaminating method of sedation. With appropriate sedation, fish can be more safely transported or handled for veterinary care. Sedation can minimize stress or physical damage caused by handling and capture, and prepare fish for the deeper planes of anesthesia necessary for more extensive handling, longer transport, or invasive procedures. This study assessed the efficacy of ketamine as a sedative when administered orally to three species of fish: common goldfish, Carassius auratus, ocellated river stingray, Potamotrygon motoro, and hybrid striped bass, Morone saxatilis×Morone chrysops. A practical application opportunity that became available at the end of the study demonstrated the use of oral ketamine in the transport of a single arapaima, Arapaima gigas.