The Malon had broad noses with distinctly-shaped nostrils, and their skin was a yellowish-brown color. Their foreheads had a slight ridge-like protrusion. They also had brown hair which was usually thick and wavy when they are young, but like in Humans receding hairlines and baldness occurred in older Malon. Their hair follicles grow from the mid part of their heads, just after the ridge-like pattern.
Malon waste exporters had many sores on their skin due to theta radiation exposure. The Malon used analeptic compound injections to counter the freighter blight, but while the treatment kept them alive, it did not prevent skin scarring.
Although technologically advanced, the Malon lack the technology to recycle antimatter waste, which emitted hazardous theta radiation. Therefore, this hazardous waste was dumped in open space in vast quantities by waste export vessels. The Malon attempted to find uninhabited regions for this waste, but this was not always the case. Because ship controllers have a high profit motive to continue their transport operations, at least one person in the waste export industry has resisted efforts to develop cleaner technologies. (VOY: "Night") Some Malon engaged in waste export only worked in the industry part-time. Fesek, for example, was a sculptor by trade but could make as much profit in one waste export mission as he could have made in an entire year on his homeworld. (VOY: "Juggernaut") The Malons were self-proclaimed experts at salvage operations. (VOY: "Extreme Risk")
The Malon appear in the Pocket DS9 novel Demons of Air and Darkness, in which a Malon tanker under the command of Controller Marssi falls prey to a Hirogen hunter and is responsible for jettisoning its antimatter waste through an Iconian gateway into the Europa Nova system.
The Malon also appear in the game Star Trek: Voyager - Elite Force, in which they are part of an alliance called the Scavengers, along with Klingons, Hirogen, and mirror universe Humans. The player has to fight his way through polluted areas filled with Malon industrial waste at one point.
In addition, the Malon appear in Star Trek Online in an expansion released in 2014, polluting space around a planet the Talaxians are about to colonize. The player must drive them away and clean up the copious theta radiation they have dumped.