Swordfish Walkthrough

A Swordfish is the three-line version of the X-Wing: a candidate confined to the same three columns across three rows (or vice versa). It can then be eliminated from those columns outside the three rows.

Sudoku board with pencil-mark candidates before applying the Swordfish technique — Before — candidates pencilled in. There is a Swordfish with the number 7.

There is a Swordfish with the number 7. Applying the Swordfish eliminates 9 candidates (struck out in red below; any solved cells shown in green).

The same Sudoku board after the Swordfish technique eliminates 9 candidates — After applying the Swordfish.

Learn the Swordfish technique →Practice it on a real puzzle →