Just a random thought that popped in my mind, I´m sure you´ve heard the term concrete shoes, mobsters choice of swimwear for fellas with rodent traits and other individuals that ran afoul of them.
But, is there any truth to any of it?, fish rolled up in newspapers, snitches and rivals sleeping with the fishes and all that jazz?
How about other, err, trademark ways of offing people?
It’s ‘cement shoes’. Capish?
It’s “capiche”. Capiche?
I can’t find a cite, but my gut tells me that a long heavy anchor chain tied to your feet has been used more than once in real life.
OK, this is third hand, but here goes:
My coworker is in the Coast Guard reserves and got this story from an older sailor. In the 60’s the old guys ship found a dead guy nailed to a cross floating offshore. The whole thing had been chained to weights but the bloating of the corpse had made it buoyant enough to surface. The victim was a black male and it was apparently the work of the black panthers. The body showed evidence of torture prior to crucifixion and it was believed that he was executed as a “traitor.” I don’t know how such expert knowledge was available to the Coast Guard, but you’ve been told what I was told.
A murder like the OP describes happened where I grew up. They did the whole concrete thing and dumped it in Lake Sammamish. The really weird part of the story is that the people were caught and it turned out to be a person that owned a Hair Salon right near my house. People in my neighborhood had been going there for years.
I googled and couldn’t find the story, the guys name was David (the killer), hair salon was David’s East, and I think the whole thing was drug related.
The OP brings to mind the story of that American union bloke, name forgotten.
Wasn’t he found with cement shoes on?
I’m assuming that you’re thinking of Jimmy Hoffa?
His body has never been found, but a spokesman for the Teamsters says that Hoffa will always be a cornerstone of the organization.
They have also in the past said that he’s the foundation of everything they do and the baseline against which all others must be measured.
That’s the feller.
I thought he’d been found yonks ago or am I thinking of a Jim Carey film
Hey, the lyrics of AC/DC Dirty Deeds say “concrete shoes” and that’s good enough for me. 
So, from the answers so far it seems that sending people to sleep with the fish isn’t (or wasn’t, I hope!) such a common practice for the mafia as it’s been imprinted in popular culture, right?
And about the coincidence with Hoffa’s disappearence anniversary… I deny everything.
Well you would, wouldn’t you?
::looks around furtively::
These days, a “gangland execution” style killing means shot in the head at short range with a small caliber pistol, often behind one ear. It isn’t very elegant, but it’s relatively quiet and reliable. In most cases, the body is found where it fell, with no attempt to hide it.
Actually, it’s “capisc " or “capisce”, capisce? 
(from the Italian verb “capire”).; 'sce” is pronounced like “sh” in English (or “che” in French, which is what your spelling is closest to).
/nitpick
Re the OP - I got nothin’.
garroting is pretty traditional
Putting a guy in a sack.
In order to put a guy in a sack properly he has to be unconscious. This can be achieved by buying him a drink and slipping a powder into it. Alternatively, you can tap him on the back of the head with a blackjack (which saves the expense of buying the drink).
From Sense of Humour by Damon Runyon:
Anyway, after the guy is asleep, you double him up like a pocketknife, and tie a cord or wire around his neck and under his knees. Then you put him in a gunny sack, and leave him some place, and by and by when the guy wakes up and finds himself in the sack, naturally he wants to get out and the first thing he does is to try to straighten out his knees. This pulls the cord around his neck up so tight that after a while the guy is all out of breath.
Runyon was intimately acquainted with various prominent citizens of the underworld and it’s unlikely he made this up.
How widespread this practice was in the thirties and forties, I cannot say.
And to convey the word in English, ‘capish’ is fine. You got a problem wid dat?
Around here, you just shoot 'em in the head and dump 'em in a canal or ditch.
I think the cement thing would just lead to the rest of the body detaching and floating back up after it’s been gnawed on a bit.
As indeed is concrete a close enough synonym for cement.