Swordfish Sudoku Technique — 3×3 Fish Pattern Guide

A Swordfish can be found when three or match up in parallel . We can then safely remove candidates in the opposite lines.

How it works

Find the first Row

This Row has a — digit 8 appears in two or three cells.

Find another matching Row

This Row also has 8 in two or three cells — and in the same Columns.

Find the third matching Row

This Row lines up too — all three Rows share exactly three Columns.

Only possible outcomes

We know 8 must land once in each Row.

Spot the relationship

No matter which order we place 8 in the Rows, each of the Columns will have one 8 too.

Eliminate other cells

We can safely remove other 8 from the Columns.

7
1
4
9
2
6
3
1
5
9
1
5
8
9
1
8
9
1
5
8
9
6
8
5
1
2
9
4
1
2
9
7
1
3
9
1
3
9
9
1
9
3
1
7
9
8
1
5
9
2
1
6
9
4
8
1
4
5
6
9
7
2
4
9
2
6
2
4
6
9
3
1
2
4
6
9
1
5
6
9
3
4
5
9
1
3
4
5
6
9
1
9
2
3
4
8
9
2
6
7
1
4
5
6
8
9
1
2
4
6
8
9
1
5
6
8
9
3
4
9
2
9
5
1
3
4
6
9
4
6
8
9
4
6
7
8
9
6
8
9
2
3
9
3
7
9
8
9
1
2
3
4
7
2
6
7
1
2
3
4
6
1
4
6
8
9
5
1
3
6
8
9
1
3
5
4
2
3
9
2
3
5
6
6
8
3
6
8
7
3
5
9
3
5
7
9
6
1
3
4
7
5
7
8
1
4
9
1
3
4
9
2
Find the first Row
This Row has a — digit 8 appears in two or three cells.
7
1
4
9
2
6
3
1
5
9
1
5
8
9
1
8
9
1
5
8
9
6
8
5
1
2
9
4
1
2
9
7
1
3
9
1
3
9
9
1
9
3
1
7
9
8
1
5
9
2
1
6
9
4
8
1
4
5
6
9
7
2
4
9
2
6
2
4
6
9
3
1
2
4
6
9
1
5
6
9
3
4
5
9
1
3
4
5
6
9
1
9
2
3
4
8
9
2
6
7
1
4
5
6
8
9
1
2
4
6
8
9
1
5
6
8
9
3
4
9
2
9
5
1
3
4
6
9
4
6
8
9
4
6
7
8
9
6
8
9
2
3
9
3
7
9
8
9
1
2
3
4
7
2
6
7
1
2
3
4
6
1
4
6
8
9
5
1
3
6
8
9
1
3
5
4
2
3
9
2
3
5
6
6
8
3
6
8
7
3
5
9
3
5
7
9
6
1
3
4
7
5
7
8
1
4
9
1
3
4
9
2
Find another matching Row
This Row also has 8 in two or three cells — and in the same Columns.
7
1
4
9
2
6
3
1
5
9
1
5
8
9
1
8
9
1
5
8
9
6
8
5
1
2
9
4
1
2
9
7
1
3
9
1
3
9
9
1
9
3
1
7
9
8
1
5
9
2
1
6
9
4
8
1
4
5
6
9
7
2
4
9
2
6
2
4
6
9
3
1
2
4
6
9
1
5
6
9
3
4
5
9
1
3
4
5
6
9
1
9
2
3
4
8
9
2
6
7
1
4
5
6
8
9
1
2
4
6
8
9
1
5
6
8
9
3
4
9
2
9
5
1
3
4
6
9
4
6
8
9
4
6
7
8
9
6
8
9
2
3
9
3
7
9
8
9
1
2
3
4
7
2
6
7
1
2
3
4
6
1
4
6
8
9
5
1
3
6
8
9
1
3
5
4
2
3
9
2
3
5
6
6
8
3
6
8
7
3
5
9
3
5
7
9
6
1
3
4
7
5
7
8
1
4
9
1
3
4
9
2
Find the third matching Row
This Row lines up too — all three Rows share exactly three Columns.
7
1
4
9
2
6
3
1
5
9
1
5
8
9
1
8
9
1
5
8
9
6
8
5
1
2
9
4
1
2
9
7
1
3
9
1
3
9
9
1
9
3
1
7
9
8
1
5
9
2
1
6
9
4
8
1
4
5
6
9
7
2
4
9
2
6
2
4
6
9
3
1
2
4
6
9
1
5
6
9
3
4
5
9
1
3
4
5
6
9
1
9
2
3
4
8
9
2
6
7
1
4
5
6
8
9
1
2
4
6
8
9
1
5
6
8
9
3
4
9
2
9
5
1
3
4
6
9
4
6
8
9
4
6
7
8
9
6
8
9
2
3
9
3
7
9
8
9
1
2
3
4
7
2
6
7
1
2
3
4
6
1
4
6
8
9
5
1
3
6
8
9
1
3
5
4
2
3
9
2
3
5
6
6
8
3
6
8
7
3
5
9
3
5
7
9
6
1
3
4
7
5
7
8
1
4
9
1
3
4
9
2
Only possible outcomes
We know 8 must land once in each Row.
7
1
4
9
2
6
3
1
5
9
1
5
8
9
1
8
9
1
5
8
9
6
8
5
1
2
9
4
1
2
9
7
1
3
9
1
3
9
9
1
9
3
1
7
9
8
1
5
9
2
1
6
9
4
8
1
4
5
6
9
7
2
4
9
2
6
2
4
6
9
3
1
2
4
6
9
1
5
6
9
3
4
5
9
1
3
4
5
6
9
1
9
2
3
4
8
9
2
6
7
1
4
5
6
8
9
1
2
4
6
8
9
1
5
6
8
9
3
4
9
2
9
5
1
3
4
6
9
4
6
8
9
4
6
7
8
9
6
8
9
2
3
9
3
7
9
8
9
1
2
3
4
7
2
6
7
1
2
3
4
6
1
4
6
8
9
5
1
3
6
8
9
1
3
5
4
2
3
9
2
3
5
6
6
8
3
6
8
7
3
5
9
3
5
7
9
6
1
3
4
7
5
7
8
1
4
9
1
3
4
9
2
Spot the relationship
No matter which order we place 8 in the Rows, each of the Columns will have one 8 too.
7
1
4
9
2
6
3
1
5
9
1
5
8
9
1
8
9
1
5
8
9
6
8
5
1
2
9
4
1
2
9
7
1
3
9
1
3
9
9
1
9
3
1
7
9
8
1
5
9
2
1
6
9
4
8
1
4
5
6
9
7
2
4
9
2
6
2
4
6
9
3
1
2
4
6
9
1
5
6
9
3
4
5
9
1
3
4
5
6
9
1
9
2
3
4
8
9
2
6
7
1
4
5
6
8
9
1
2
4
6
8
9
1
5
6
8
9
3
4
9
2
9
5
1
3
4
6
9
4
6
8
9
4
6
7
8
9
6
8
9
2
3
9
3
7
9
8
9
1
2
3
4
7
2
6
7
1
2
3
4
6
1
4
6
8
9
5
1
3
6
8
9
1
3
5
4
2
3
9
2
3
5
6
6
8
3
6
8
7
3
5
9
3
5
7
9
6
1
3
4
7
5
7
8
1
4
9
1
3
4
9
2
Eliminate other cells
We can safely remove other 8 from the Columns.

All Hints

Unlock hints to find
the Swordfish on your board.

Next up

JellyfishExtreme