The Rodian Karstag was a predator, native to Rodia, that inhabited swampy and damp forests. An adult was about 1.5 meters in height at the shoulder and between 4 and 5 meters long. Despite the animals' bulky appearance, they were deceptively fast creatures. They had scaled bodies that were supported by four powerful membranous webbed feet that aided locomotion in water and swamps.
The karstag had an elongated neck and a triangular head. Its eyes were located at the top of head to allow visibility while the creature was submerged. Its mouth was lined with teeth and included one prominent incisor at the roof of the mouth and two at the bottom. A bone-like club with large spikes at the end of its tail was used by the animal as a weapon and was what made the Rodian karstag so dangerous.