The Nenlar are a humanoid species that looked similar to the Cardassians save for the species’ trademark arrogance. They are about two and a half meters tall, and quite powerfully built. They possessed small, iridescent scales that covered what flesh was visible, long black hair, and the females had breasts, indicating that they were mammalian.
Their hands had long, tapered fingers and a peculiar hornlike growth protruding from the wrists. In addition, they had slightly elongated mouths similar to muzzles and they had vestigial, stumpy tails. (VOY - Gateways novel: No Man's Land)
Using faster-than-light travel, they searched for ways to enrich their world-new crops, new technology, new ideas. Many intrepid souls left their homeworld altogether, to scratch out new lives for themselves elsewhere.
Due to their traumatic experience with the Iudka, the Nenlar have an ingrained fear of being dominated and taken advantage of again. Their interactions with other species make them appear overly anxious and fearful. (VOY - Gateways novel: No Man's Land)