A Nygean prison ship was a starship operated by the Nygean Detention Force to transport prisoners from one planet to another, sometimes for execution. Nygean prison ships were capable of warp 8.2 and equipped with escape pods.
In 2377, such a prison ship under the command of warden Yediq suffered a ruptured conduit, flooding it with plasma radiation. Luckily, the crew was rescued by the USS Voyager, which was nearby when they issued a distress call. Its (surviving) complement was comprised of three Nygean guards, three Nygean prisoners, and five Benkaran prisoners. (VOY: "Repentance")