1. Extreme #168
After standard eliminations and Setti on 8 (row G must not contain 8) we get the following key position:
-- if J2=7 - G2=1, J5=1, J7=34 contradiction to Setti on 5 (all rows must contain 5),
so J12=56, eliminates 5 from J7
-- Setti on 7 - row J does not contain 7 - col 6 must not contain 7, removes 7 from DFH6
-- We can exclude 4 from H1 and H2 by testing the two options for H3:
if H3=3 - H5=4
if H3=2 - Setti on 2 - G1=6, J2=6, E3=6, A4=6, C5=6, B5=5, - B2=4
and J1=5 - C1=4
So in both cases H12 cannot contain 4
-- Jellyfish 4 (cols) on BCDF1234, eliminates 4 from B9, D 6789, F689 - F6=6
removes 6 from F13489 and DH6
The rest is comparatively easy; only singles and naked pairs/triples needed,
no Setti nore fishes