Sashimi Jellyfish
A Sashimi Jellyfish is a fish pattern, formed by an incomplete Jellyfish which is stabilized by additional candidates in a box that intersects with one or more lines of the defining set. It is a single-digit solving technique.
Here is a fish diagram that shows a Sashimi Jellyfish in the columns:
The candidates marked X form an incomplete Jellyfish pattern, with 4 columns having candidates in only 4 rows. This pattern would not be stable with only a single candidate in column 2 if the 2 candidates marked F were not present. These candidates are the fin. Either one of the F candidates is true, or the Jellyfish degenerates into a single in r6c2 and a Swordfish in the remaining 3 columns. The candidates marked * are removed in both cases, allowing us to eliminate them from the grid.
Considerations
A pure Sashimi Jellyfish is hard to find. Several vertices need to be removed to form an incomplete Jellyfish. The pattern you see in the diagram is only one of the ways to reduce the Jellyfish. However, other reductions often lead to alternative eliminations, which are easier to spot than the Sashimi Jellyfish.
