Fish
How it works
An X-Wing stretched to three. Three rows where a digit's remaining cells all fall inside the same three columns — each row needs two or three of them, not necessarily all three — must place the digit once per row, one in each column. Every other cell of those three columns can therefore lose the digit. As with X-Wing, rows and columns swap freely.
Try it
Digit 9 is pinned down by rows 1, 6, and 8. Let's pencil in the highlighted cells — every place 9 can still go in those lines — then see why it can't sit anywhere else in columns 6, 7, and 9.
1
2
5
4
3
3
9
8
5
2
6
1
7
4
4
7
6
3
5
6
9
4
3
5
7
4
1
9
7
3
6
8
3
7
6
4
5
3
4
6
8
4
1
3
5
1
2
6
5
4
3