Expert technique · Technique Academy

Jellyfish

A Jellyfish is the fish family at its largest: a digit confined to the same four columns across four rows, with only two to four places in each row. It is rare enough that finding one is cause for a small celebration.

Professor Cryptic, the owl who teaches in the app
Professor Cryptic is thinking

The reasoning

Why does the Jellyfish work?

The four rows must use all four columns for this digit, so no other cell in those columns can hold it. Strike it and enjoy the view.

A worked example

What does the Jellyfish look like on a real board?

Jellyfish worked exampleA sudoku board with pencil marks. The Jellyfish uses R2C2, R2C6, R5C3, R5C4, R7C4, R7C6, R9C2, R9C3 and digit 2 (rows 2, 5, 7, 9). The move strikes candidates 2 in R3C2, 2 in R4C3, 2 in R6C3.258459763129325965912858471259742835862925125973462984628289573173289628142959732862815484135927662525147983
The move strikes candidates 2 in R3C2, 2 in R4C3, 2 in R6C3. Digit 2, rows 2, 5, 7, 9.
  • Cells that form the pattern
  • Cells that lose a candidate
  • Struck digit: ruled out

Make it stick

How can you practise the Jellyfish?

The Technique Academy in Cryptic gives every technique its own lesson and 5 practice boards that need exactly this move.

Get it onGoogle PlayPlay Cryptic on the web

Further reading: HoDoKu's page on this family of techniques.

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