Mirrored from Sudopedia, the Free Sudoku Reference Guide
When there is only a single candidate in the fin, Sashimi X-Wings can be interpreted in two ways, according to the following diagram:
With an extra candidate in r2c8, this would be a Finned X-Wing in columns 2 and 8, rows 2 and 8, with the fin in box 3. With an extra candidate in r3c2, this would be a Finned X-Wing in columns 2 and 8, rows 3 and 8, with the fin in box 1.
The same pattern can also be interpreted as a Skyscraper.
With 2 candidates in the fin, there is only one way to interpret the pattern:
This pattern can only be interpreted as a Sashimi X-Wing with the 2-candidate fin in box 3.