Jellyfish
Expert Removes candidates Used in: Sudoku, Killer Sudoku
The four-line fish: a digit across four rows is confined to the same four columns. As with the X-Wing and Swordfish, the digit is then eliminated from those four columns in every other row.
How to spot it
The four-by-four fish: a digit across four rows confined to four columns.
What you can conclude
Remove the digit from those four columns everywhere else.
Worked example
Four rows confine 2 to four columns — the same logic as an X-Wing, one size larger.