Swordfish - The Larger Fish Pattern You Meet in Expert Sudoku
Swordfish is the three-row or three-column extension of X-Wing. Instead of building a rectangular pattern from two rows and two columns, Swordfish tracks one digit across three rows or three columns. If that digit appears in only two or three cells within each of those rows, and all candidate positions align within the same three columns, you can eliminate the digit from other cells in those columns.
That definition sounds heavy, but the core idea is simple: the fish locks a digit into a small set of rows and columns, so any duplicate candidates outside the fish become impossible.
How Swordfish Extends X-Wing
If X-Wing is a 2x2 structure, Swordfish is a 3x3 structure. You still work digit by digit, counting candidate positions row by row or column by column. The difference is scale and visual complexity. This makes Swordfish harder to see and much rarer than X-Wing.
Where It Appears
You are unlikely to need Swordfish in easy or medium sudoku. It belongs to Expert and Master Sudoku, especially on boards where candidate density stays high for a long time.
Frequently Asked Questions
What is Swordfish in sudoku?
It is a fish pattern that uses three rows and three columns for one digit.
How is Swordfish different from X-Wing?
Swordfish is the larger, three-line version of the same fish logic.
When does Swordfish appear?
It appears in expert and master puzzles when simpler techniques stop producing progress.
Next Steps
Continue Your Sudoku Path
These guides and puzzle pages are selected for the page you are on, so you can move naturally to the next skill, level, or practice route.
Technique Path
Use the hub, check the prerequisite, or continue to the next pattern in the solving sequence.
Practice This Technique
The fastest way to lock in a pattern is to use it on the difficulty levels where it naturally appears.