Too many people do this for not one of them to be on these boards. So fess up. Admit it. Why do you do it?
What is a “dead fish” handshake? 
It’s when you limply offer the other person your hand and make them shake it. (FTR, I don’t do this.)
In that case I don’t do it either.
I have arthritis, and it is very painful to receive a “bonecrusher” handshake. But dead fish handshakes creep me out, so I try to match whatever pressure is offered, even though it hurts.
When someone offers me the dead fish, I squeeze very carefully and gently, because that person may have arthritis, too.
I do it because I just plain hate giving handshakes. I pretty quick to release as well. Just a quick clasp, tug, and release. See ya later.
I was going to address this in the OP but I decided to let someone mention it first.
Why not just be a man and not shake hands? I bet 99 out of 100 men would respect you more for saying “I don’t shake hands” than for giving them the dead fish.
I mean there is really no greater sin in my book. Either grab my hand like a man or don’t touch me. The dead fish gives me the serious heebie-jeebies.
I view a dead fish handshake as a lack of enthusiasm/interest. Could be just anecdotal, but all the people that get along really well with me give firm handshakes.
A handshake doesn’t have to be long, but come on, my hand isn’t made of paper mache! A little squeeze doesn’t hurt! 
It’s even worse when their hands are cold and sweaty. Yuck.
I have to admit, I’m a crusher. I try really hard not to, and mostly succeed, but sometimes my brain gets stuck on “pulp”. “Whoops, sorry there, grandma.”
Most of the dead fish handshakes I’ve gotten have been from women or skinny and short men. Maybe for the ladies they’re just not used to shaking hands as much, but C’mon folks! Use the same amount of force that you would use picking up your coffee mug and make people think you give a damn! I don’t expect you to crush my hand, but at least put a little effort into it.
I never willingly give a dead-fish handshake, but I do find I’m the occasional victim of a premature grabber. If you close your hand before the webbing of my hand hits yours, you’ll be holding a dead fish because I’ve got hardly any leverage.
It’s very easy to extend a firm hand without squeezing the other person unmercifully. Your hand can be firm and muscled, thus avoiding any unpleasant limpness, yet it doesn’t move into a grasping or crushing mode. Really, it’s very simple.
Eh, sorry Barbarian, didn’t see your post until review… yeah, those damn premature grabbers are the worst. Anybody that treats an introduction as an opportunity to be agressive loses major personality points with me. It’s a hello, not a freakin’ contest.
It’s a dead heat between which I dislike more, a dead fish or a premature grab.
I mean, how the hell do you expect me to shake your hand if I only have the thumb and fore finger to clasp with?
I’ve always given firm, rather manly handshakes. But I’ve developed arthritis in my right hand in the last few years. And while I avoid shaking hands now, sometimes you just can’t escape one thrust out at you like you’re going to get away. And those are usually the bonecrushing type.
So it’s not so much of a “dead fish” as an involuntary flinch. I don’t like to do it, but I also don’t like to have to rip my poor throbbing hand out of someone’s bear trap. Ow.
I can’t stand limp handshakes. I realize there are some that find a firm handshake painful (like the arthritis sufferers that posted previously), but I notice I often get them from people that are either very uninterested or very shy.
Cripes, people, shake the hand I give you, don’t slap a lukewarm trout in my palm!
This is one of my pet peeves too. I’m a woman and I believe in firm handshakes. I’d rather not shake hands at all than get stuck with a limp shake! There is nothing wrong with being firm!
As a young girl (up untill 17) I always gave dead fish handshakes. Most young girls I meet give them too.
It was mainly shyness and passiveness. It is the same attitude as sitting in a corner and wait till someone speaks to you, instead of walking up to someone and chat them up.
It is just easier to let the other person take the initiative. In handshakes, just as in everything.
Handshakes aren’t as common as they once were, so I think a lot of people are out of practice. A lot of the premature grabbers and dead fish are people who think that a handshake is all in the fingers. Actually, it is more than half in the palm.
You’ve got to make sure the palms are in contact before curling the fingers around. That way, both people are in position to apply as much firmness as they prefer, without having to assert themselves against the other person’s fingers.
One should also take note of whether the other person is wearing rings. If they are, it is even more important that you squeeze the palm, as squeezing the fingers even a little can be quite painful.
I prefer not to shake hands for several reasons. Here is one of 'em:
One day at work I just came out of the bathroom with my hands still somewhat wet (from washing). I ran into a vice president of the company who was with some clients. She stopped me and thanked me for my contribution on a recent high-profile project then stuck out her hand to shake.
What was I to do? So I shook it.
I probably should have offered to go back and get her a towel.
Instead I shrunk about 3 sizes and crawled to my cube