Fish Variants (Finned X-Wing, Sashimi etc.)

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Fish Variants (Finned X-Wing, Sashimi etc.)

What It Is

Fish variants adjust fish patterns when extra or missing candidates appear. Finned fish add a “fin” cell; sashimi fish are incomplete fish treated with an implicit fin—both allow eliminations despite the imperfect pattern.

When to Use

Advanced stages when standard X-Wing/Swordfish is almost present but slightly off—extra candidate (fin) or missing corner.

How to Apply (Step-by-Step)

  1. Find an almost fish with an extra candidate (fin).
  2. Identify fin and base sets.
  3. Use fin’s box/line interaction: eliminate the candidate from cells that see the fin within the fish’s elimination zone.
  4. For sashimi, treat the lone candidate as a fin and eliminate where the missing corner would be.
  5. Re-scan after eliminations.

In a finned X-Wing on 7 with fin at r1c8, eliminate 7 from cells like r3c8 in the fin’s box/column intersection—fin true or false, those cells can’t be 7.

See also

Scanning / Cross-Hatching Single Candidate (Naked Single) Single Position (Hidden Single) Naked Pairs / Triples / Quads Hidden Pairs / Triples / Quads Pointing Pairs / Triples (Locked Candidates Type 1) Box–Line Reduction (Locked Candidates Type 2) X-Wing Swordfish Jellyfish XY-Wing XYZ-Wing W-Wing Alternating Inference Chains (AICs) Forcing Chains / Forcing Nets Nishio Coloring Multi-Coloring Uniqueness Techniques (Unique Rectangle etc.) Fish Variants (Finned X-Wing, Sashimi etc.) ALS Techniques (ALS-XZ, ALS Chains) Sue de Coq Pattern Overlay / Template Method
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