Jellyfish Sudoku Technique — 4×4 Fish Pattern Guide

When a digit lines up in four parallel , and four opposite lines, we can safely remove candidates in the opposite lines.

How it works

Find the first Row

Digit 7 appears in two, three, or four cells in this Row.

Find another matching Row

This Row also has 7 in two, three, or four cells, and in the same Columns.

Find the third matching Row

This Row lines up too. Still in the same Columns.

Find the fourth matching Row

This Row lines up too. All four Rows share exactly four Columns.

Only possible outcomes

We know 7 must land once in each Row.

Spot the relationship

No matter which order we place 7 in the Rows, each of the Columns will have one 7 too.

Eliminate other cells

We can safely remove other 7 from the Columns.

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

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