Bloaters are a variety of feral ghoul found primarily in Four Seasons, in and on the banks of the radioactive, sludge-stream that was the Trinity River. They might also exist near other highly contaminated, slow-moving bodies of water.

Bloaters are aptly named; their bodies are "water-logged," with toxic sludge and they're covered with caked on layers of dried mud, making them appear fatter than normal ghouls. Underneath the coating of sludge, they resemble the swamp ghouls of Louisiana and Point Lookout.

They possess a goat-like constitution that allows them to subsist on nearly anything, though they favor live prey when they can get it. Bloaters do not typically pursue their quarry like typical ferals, however: they prefer to lie submerged in sludge, and ambushing any who approach. When not waiting for food to show up, Bloaters like to sun themselves, floating on their backsides and allowing evermore muck to accumulate and dry on their bodies.

The most peculiar behavior of Bloaters is their attitude towards non-feral ghouls. While typical feral ghouls ignore ghouls, allow themselves to be herded by them, or attack them (typically if they're in the company of humans); Bloaters will actually chase down ghouls and drag them back to their territory. Any unfortunate ghoul caught by Bloaters will be subjected to near-drowning as the Bloaters hold them underneath toxic sludge again and again until the ghoul dies or turns feral. It usually takes years of near-mindless cavorting in muck before a feral ghoul soaks up enough sludge to become a Bloater in their own right.