Mutant cat fish
and mutant leeches that would have been in van buren.
all kinds of neat things could be in Lake Mead.
OH
MY
GOD!!!
Bethesda!! Put a giant me in Lake Mead

My last name is Mead afterall..How epic would that be

On a more serious note, I think Sea Monsters would be awesome! We've had Mirelurks and that, but now, near Las Vegas...I think we should have MASSIVE Crabs, or Octopuses or Sharks or something