Ready to put the Jellyfish into action? This page is designed for you to practice and master Jellyfish with positions from real Sudoku puzzles.
Every board above is a position from a real puzzle where the Jellyfish is the next step. Tap the candidates it removes (or select a cell and press the digit) and press Check. If you’re stuck, Show me gives the answer and Next puzzle loads another. Want to watch one first? Switch to Worked example.
Quick Reminder: What is a Jellyfish?
A Jellyfish is the four-line version of the X-Wing and Swordfish. When a digit’s places in four rows all fall inside the same four columns, those four rows use up the digit in those columns. You can remove the digit from the rest of the four columns (and the same works with rows and columns swapped).
Want a full step-by-step guide? Read the Jellyfish technique article
How to Practice
- For one digit, find four rows (or columns) where its places, taken together, cover only four columns (or rows).
- Remove the digit from the other cells of those four columns (or rows).
- On the board, tap each of those candidates to remove it.
- Press Check. On your first try you see how many you found; on the second, the ones you missed get a dashed ring.
Start Practicing on Full Puzzles
Once you can find the Jellyfish on most boards without pressing Show me, take it into a full game. Evil puzzles are where this technique starts to come up, and the step-by-step solver will name the technique each time you get stuck.