Finned Jellyfish: four-line fish with an escape
A finned Jellyfish is a size-four fish plus one or more extra base candidates outside the four cover columns.
Key idea
A target is removable only if the fin sees it and the underlying finless Jellyfish would also eliminate it.
See the move, step by step
Treat R1C2 as the fin on a candidate-7 Jellyfish.
Step 1 of 4
Find a near four-line fish
Rows 1, 4, 7, and 8 nearly confine candidate 7 to four cover columns.
Step 2 of 4
Separate the fish from its fin
Eight candidates form the Jellyfish skeleton. The extra 7 at R1C2 is the fin.
Step 3 of 4
Intersect the fin and fish cases
R2C3 sees the fin through box 1 and lies in a Jellyfish cover column, so both cases eliminate its 7.
Step 4 of 4
Keep the cleanup local
Remove 7 only from R2C3; the fin prevents unrestricted eliminations across all cover columns.
Try it on today's puzzle
Search smaller fish first. For every proposed elimination, verify both cases independently: fin true and fin false.
Play today