Tanker

From Memory Alpha, the free Star Trek reference

In starship classification, a tanker is a starship with a limited role. Similar in purpose to a freighter, tankers are designed to carry large amounts of bulk fuel or other liquid-type substances.

Captain Korok commanded a D5-class deuterium tanker during the 2140s and 2150s. During this time, he harassed the residents of the small deuterium mining colony operated by Tessic, taking the majority of the deuterium for his own ship. (ENT: "Marauders")