Practise the Jellyfish

The four-row fish. Valid, beautiful, and almost never necessary.

8 real positions, each taken from an actual puzzle at the moment this was the cheapest move available. Two steps: find the cells that form the pattern, then find the candidate it rules out. A near miss tells you how many you had right, so getting it wrong is worth something.

Select the cells that form the pattern, then check. 1 / 8

6	12	125	9	3	8	17	157	4
3	9	8	7	14	145	6	15	2
7	4	15	6	12	125	8	9	3
8	7	12	3	6	12	9	4	5
14	126	46	5	127	9	3	8	17
5	3	9	8	147	14	2	17	6
9	8	3	4	5	6	17	2	17
2	5	7	1	9	3	4	6	8
14	16	46	2	8	7	5	3	9

How to spot it

Four rows whose homes for one digit span exactly four columns. If you find one before finding something simpler, check again — there is usually something simpler.

Full explanation on the Jellyfish reference page.

Practise something else

Swordfish An X-Wing with three rows and three columns instead of two.
X-Wing One digit, two rows, two columns. The first pattern that spans the whole grid.

6	12	125	9	3	8	17	157	4
3	9	8	7	14	145	6	15	2
7	4	15	6	12	125	8	9	3
8	7	12	3	6	12	9	4	5
14	126	46	5	127	9	3	8	17
5	3	9	8	147	14	2	17	6
9	8	3	4	5	6	17	2	17
2	5	7	1	9	3	4	6	8
14	16	46	2	8	7	5	3	9

6	12	125	9	3	8	17	157	4
3	9	8	7	14	145	6	15	2
7	4	15	6	12	125	8	9	3
8	7	12	3	6	12	9	4	5
14	126	46	5	127	9	3	8	17
5	3	9	8	147	14	2	17	6
9	8	3	4	5	6	17	2	17
2	5	7	1	9	3	4	6	8
14	16	46	2	8	7	5	3	9

6	12	125	9	3	8	17	157	4
3	9	8	7	14	145	6	15	2
7	4	15	6	12	125	8	9	3
8	7	12	3	6	12	9	4	5
14	126	46	5	127	9	3	8	17
5	3	9	8	147	14	2	17	6
9	8	3	4	5	6	17	2	17
2	5	7	1	9	3	4	6	8
14	16	46	2	8	7	5	3	9