I forget where the original "Salmon of Doubt" came from; maybe Douglas Adams? Anyway, Dale suggested that it could be accompanied by the Trout of Contrition (or is that something I picked up from #c?).
I mentioned sparkindarkness's Haddock (clients who are particularly stupid are said to merit a good Haddocking).
And then Dale came up with the Swordfish of Shut the Fuck Up, which I thought was an admirable addition to the collection. I think it should primarily be self-applied, not applied to others, but on the other hand, I could see "/me hands X a swordfish" as a gentle way of suggesting, "You might want to quit while you're behind, there, friend".