At the bidding of their master, Darkseid, the Deep Six seemingly exists for the sole purposes of combat and terrorism in his name. All six fish-like members possess superhuman strength as well as the ability to breathe and function underwater.
Aquaman and his allies, Koryak and Dolphin have battled and seemingly killed all of Deep Six.
Orion killed all of the Deep Six during a battle on Earth. However, a member named Slig returned only to be killed by Orion again. It has since been revealed that the team has been resurrected several times over the years whenever Darkseid has use for them.