Swordfish Explained
Swordfish is X-Wing's 3-row, 3-column cousin. The concept is the same as X-Wing, but because it involves 3 rows and 3 columns, it is harder to spot.
X-Wing vs. Swordfish
X-Wing
2 rows × 2 columns rectangle
Swordfish
3 rows × 3 columns pattern
How to Spot One
1. Pick a specific number to track
2. Look for rows where that number has only 2–3 possible positions
3. Check if 3 rows share the same 3 columns for their candidate positions
4. If so, those 3 columns form a Swordfish — eliminate that number from other rows in those columns