A Byzatium in a holodeck
The Byzatium were a spacefaring species that conducted business at Deep Space 9. (DS9: "Defiant")
They originated from the planet Byzatium. They were notable to be much heavier than the vast majority of sentient beings even if their volumes were comparable to that of humans or Romulans. For instance, Relm's mass in 2384 was 762 kg whereas a female human of similar volume would have a mass of about one-tenth as much. They were also notable to be physically exhausted quite rapidly even when they only did a few minutes of light walking. Pazzo had difficulty adapting to Byzatium medicine. (RIS Bouteina)
Byzatium could drink large amounts of bloodwine, doses that could be lethal to humans. ("Marianela")
External link
Byzatium article at Memory Alpha, the canon Star Trek wiki.