What is the English version of the Vietnamese idiom "như cá nằm trên thớt" - "like a fish on cutting board"

We have a Vietnamese idiom, "như cá nằm trên thớt" - literally, "like a fish on cutting board". My apology for the rough translation because I regard myself as an English learner who is above the average a bit. The meaning of the idiom is: implying a dangerous and almost unescapable situation in which a person's life or fate is in someone's hands and seriously threatened.

I have looked for a similar expression in the idioms section of thefreedictionary and other websites such as merriam-webster and the OED but they appear to have other expressions that are not related to the word "fish".

Is there an English version or a metaphor of the mentioned idiom?

Besides, many presume the Vietnamese idiom to be exactly identical to the Japanese one. However, they do have a slightly different meaning regarding their contexts.

Solution 1:

I would say like a lamb led to slaughter is the closest in meaning. The lamb is symbolic for its innocence. It will follow you happily, not knowing you are taking it to die. So this idiom implies a naivety on the part of the lamb, when in fact its life is in the hands of another. That seems to be the same as your meaning for the fish on the cutting board.

Another one we use is to be a sitting duck. The duck is unaware of the danger it is in by remaining still. That makes it much easier to shoot.

The shooting fish in a barrel idiom is more implying that some task is very easy. It is not used from the fish's perspective.

Solution 2:

The closest expression I can think of is

have/put your head on the (chopping) block

That is 'to risk a bad thing happening to you by doing something or helping someone.'

Other animal-based analogies which could be used in a similar context to the one you mention, but have a slightly different use are 'like pigs to the slaughter' and 'like fish in a barrel.'

edit: As Joe has pointed out in comments, 'like a sitting duck' is also a good match. The key difference between the chopping block and the duck comparison is whether the agent (person/company/team etc) in question is aware of their own vulnerability and/or has put themselves there deliberately.

Solution 3:

You could be up a creek:

Also, up shit creek; up the creek (without a paddle): In trouble, in a serious predicament, as in" If the check doesn't arrive today I'm up a creek", or "The car wouldn't start, so I was up the creek without a paddle." This slangy idiom conjures up the image of a stranded canoeist with no way of moving (paddling) the canoe. [idioms.freedictionary.com]