I doub't the sally killed the fish but crabs are opportunistic feeders so if the fish was not healthy or it did lay down for some reason you never know and once it was dead all of the inverts you mentioned would have definitely gotten in on the feeding on the dead fish.
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120 Gal Reef Tank Born 12/06 160+ Lbs of Live Rock 80 Lbs Live Sand 20 Gal Sump with 15 lbs of Live Rock (2) 250w 15K MH and (4) 65w CF Atinics (6) Moonlights Aqua C EV Skimmer (3) Hydor Korillia # 3s Loads of Corals Huge clean up crew Yellow Tang Naso Tang Psych Mandarin Algae Blenny |