Swordfish:

A swordfish is a 3x3 version of an X wing
(2x2).
Swordfish: three
rows where a candidate is confined to three columns. (or vice
versa)
This swordfish is defined by the 5's in the rows 1, 6, and 9. So
the target
cells are in the columns.
In rows 1, 6, and 9, candidate 5 is confined to columns 2,4, and
6. This meets the definition of a swordfish.
The yellow squares are shown here to illustrate the
3 by 3 nature of the swordfish. But notice that the 5 is missing
from r1c2 and r9c2. This still meets the definition of a
swordfish (5's are confined to three columns in those three rows).
Candidate 5 is now committed in rows 1, 6, and 9 as
well as column 2, 4, and 6.
Any other 5's in those columns can be eliminated.
Although this is a great swordfish, can you see the
Xwing that is present here? (click here
to see it)
More swordfish information 
