It’s like shooting ducks in a barrel
Posted: January 16, 2013 Filed under: ACTION, ANIMALS, barrel, duck, shoot, THINGS | Tags: blended idioms, ducks, ducks all in a row, expressions, fish, malaphors, mixed idioms, shooting fish in a barrel, wordplay, words 2 CommentsThis is a mash up of “shooting fish in a barrel” (easy action with guaranteed success) and “all your ducks in a row” (getting everything in order), submitted by a loyal follower, the TruroTattler. Given the enormous amount of google hits, this is a common malaphor, as ducks appear to be as easy a target as fish. Also shooting mechanical ducks in a penny arcade shooting gallery is certainly playing on the mind in this one.
Malaphors 
It is almost certainly a mix of “shooting fish in a barrel” and “sitting ducks”; I doubt the ducks in a row have anything to do with it.
I think you are right, although ducks in a row might be in the mix given the “in a” words in both phrases. Sitting ducks has the same meaning as shooting fish in a barrel so I think that is the source of the malaphor. Thanks KR!