Proven Sudoku
Mutant Fish
Also called Mutant, Mutantfish.
New to this shorthand? How to read a sudoku grid explains r4c7, houses, candidates and the rest.
What it means
A fish where rows, columns and boxes can be mixed freely on both sides. The strangest shapes of all, and the counting rule is still the same.
The exact rule, for stronger players
The rule, stated exactly: A fish where base and cover sets may mix rows, columns, and boxes freely, with no orientation restriction.
What it removes: Remove d from cover cells outside the bases, subject to fins.
Why it works: The fully general set-cover statement. Only the count matters.
Worked examples
None yet. This pattern does not turn up in our daily boards, so there is no real example to show. We would rather wait than draw a fake one.
Learn these first
- Franken FishA fish where a box is allowed to join in with the rows and columns.
Related complex fish
- Sashimi FishA finned fish that is missing a corner.
- CannibalismWhen a square belongs to both halves of the fish at once.
- Complex Fish (rank framework)The fish idea, but boxes are allowed to join the rows and columns.
- Endo-FinA spare square that sits inside two parts of the pattern at the same time.
- Finned FishA fish pattern with one extra square hanging off it.
How often does it come up?
Our rough estimate: rare, and generally found by software rather than by eye.