Rishi eel

Rishi eels were predatory creatures native to the Rishi Moon, where the Republic's Rishi Station was located. During the Clone Wars, the clone trooper Cutup was devoured by a rishi eel. Later during the same incident, Clone Captain Rex killed a Rishi eel in self-defense by shooting it in the eye after he and Clone Commander Cody had escaped an ambush by BX-series droid commandos. After encountering the three surviving rookie clone troopers — Fives, Echo, and Hevy — Rex left a handprint in blue eel blood on Echo's breastplate while explaining what the term "shiny" meant. After being inducted into the 501st Legion after the battle, Fives painted an eel onto his helmet.

The eels were extremely dangerous, and thus regulations for Rishi Station personnel mandated that they not go outside under normal circumstances, as the eels were capable of killing and eating adult humans. Their skin was impervious to blaster fire, with their eyes being their only weak spot as it allowed blaster bolts to ricochet into the eel's braincase. They normally dwelled in tunnels beneath the moon's surface but adults would surface to hunt prey such as Neebray. The eels had red eyes, four large mandibles that allowed them to swallow their prey whole, blue blood, and dark blue and green skin.