Start with the idea
Start with one number. In this example, four rows need 9, and all of their possible 9s fit inside the same four columns. Those columns are reserved for the pattern's 9s, so other 9s in those columns cannot be correct.
Look for this pattern
Look for one number that lines up across matching rows and columns.
This empty board keeps the puzzle numbers out of the way so the pattern is easier to see.
Example
9
3
9
7
9
6
1
5
9
8
9
6
9
8
6
3
2
9
8
3
1
7
9
2
9
9
6
2
8
9
4
1
9
9
8
1
4
9
7
Look here firstFocus on the number 9. Four rows keep their possible 9s inside the same four columns.
This technique reviews candidates instead of solving a square right away.
Those columns are reserved for the pattern's 9s, so other 9 notes in those columns cannot be correct.
- Choose one number.
- Find four rows whose possible spots fit the same four columns.
- Remove that number from the other cells in those columns.
9s in the Jellyfish9 notes to remove
When to look for it
Use it on very advanced boards when a fish pattern spans four rows or columns.
How to use it
- Pick one digit and scan for four rows or columns.
- Confirm their note positions fit within the same four crossing lines.
- Remove the digit from other cells in those crossing lines.
Common mistakes
- Jellyfish patterns are uncommon and can be visually busy.
- Start with X-Wing and Swordfish before hunting four-line fish.