I know what some are going to say - your removing the slime (mucous) coat!  Aready criticized on another forum for using a wet terry cloth wash cloth to sedate a fish for measuring + photo and hook removal. My reply was that I place the cloth around the fish - head first - and it stops thrashing and stays quiet on a flat surface (measuring board). 

I found out last week that crappie, bass and sunfish calmed right down. Coming into contact with the wet soft texture doesn't remove its protective slime and it feels just as slippery when I release the fish. It's not like I'm wiping the fish's sides with the cloth or that it absorbs the mucous-like slime. Fish also regenerate slime after being injured by a predator or dropped on the ground, so hopefully any minimal slime lost is replaced.

It was advised that I remove the hook while the fish is in the water. Ever try doing that to the side of a flat-bottom boat causing the boat to tilt? How about hanging over the side of a fiberglass boat with a much higher deck? Last thing I want to do is go for a swim!

Holding the lower lip for hook removal was suggested, but how can you do that for small-mouthed panfish and small bass? They must not have heard of the special pliers used for that reason.
   
It was also suggested the fish be handled with wet hands. Bad enough they are slippery to begin with, making them more so with wet hands will guarantee they fall to the ground or boat bottom. Besides, I doubt too many shore anglers wet their hands which begs the question- where was the fish while they were doing this?] Do they bring along a pail of water vs. getting their feet wet & muddy when going to the water to wet their hands?!

Since these guys were so concerned, I asked these questions:
1. How many use rubber or nylon-coated landing nets? Nylon removes slime.
2. How may use barbless hooks for faster hook removal? (I don't)
3. How many use no-stretch braid in order to minimize fight time? (I do)

No one answered my questions.
Do as I say, not as I do. IMO

Examples of sedated fish that posed for the camera and then released (the top shot of a fish on the cloth after it was calmed down:
 

These fish were sedated before being measured and the flat plastic surface didn't bother them:

This is pretty much what your doing to those fish. That’s why gloves are bad.


https://m.youtube.com/wat...o&feature=emb_logo

The link didn't work.
Anyway, I wet the cloth and the fish calmed down for as long as I needed to take a photo and measurement and then released them to fight another day.

solitario lupo
This is pretty much what your doing to those fish. That’s why gloves are bad.


https://m.youtube.com/wat...o&feature=emb_logo

I'd argue the thrashing of the fish plays a pretty big role here. If they're not moving as much, I think we'd see less damage (obviously). 

do what I do - just don't catch any fish. Problem solved.

I'm concerned when fish get dropped while attempting to get the hook out, "thrashing" all over the boat bottom. Happens to me no matter how much I try to secure the fish - with dry hands no less. Maybe it's the animal lover in me, but I want to keep the trauma, panic and fear to a minimum. Calming it down with a wet cloth is the least I can do to accomplish that.

Going to try this again lol.
Pretty much if it doesn’t work what the video shows is that the glove removes the slime coat and in a couple weeks the fish get a disease and dies. So it’s very bad to use a cloth for catch and release.

https://youtu.be/a8VETvLLa0o

Strip down lather up in Wally world knockoff KY and wrasle dat fezh like a man

Good the video doesn't apply to the fish I catch or my idea of keeping them calm!
 
I've never held a fish by its tail and don't see any reason to. Again, the cloth doesn't rub the surface of the fish; fish are wrapped in it loosely, held for less than 45 seconds and released; most are released immediately once the hook is removed.
It's better than holding a fish with dry hands and letting it drop to the ground or boat floor to thrash around damaging the mucous coat for sure!
 

The animal lover in me, has me trick fish into eating a sharp hook or three, then dragging them around by their mouths…

Remember, fish are closer to bugs than they are humans in the ability to feel pain. That doesn’t mean to treat them without care. But I think a wet towel if it calms the fish is much less damaging than them flopping around on boat carpet in a landing net (which some fish that I catch do, at times treated with dry hands). I doubt all are dead within a few weeks, I know a few die when I poke a hole in their heads and clip their gills before throwing on ice. Then use a damp cloth to wipe my hands before clubbing my woman on the head. Some might die, but I doubt every fish gets a disease if they lose some slime. They are likely more susceptible, but can’t imagine they don’t produce that slime pretty quickly after being caught and doubt unless you are intentionally trying to wipe the slime off, they are going to lose so much that they get a disease. We would be seeing far more dead fish and hearing far more about this from the PFBC and others if this happened to most or many fish. Most times that I am fishing, I don’t see any dead fish floating. I would bet many that I so see are gut hooked, fought to death on a loose drag, handled too long for the hero shot or shock from being caught in too warm of water. Each of those situations, I have read can lead to higher mortality and know people do a lot. But don’t see all that many fish floating. Sure, other fish, turtles, raccoons or other could be munching them. But if these all really did that much damage, I think we’d see many more floaters.

Thanks so much Porktown for your relevant and insightful reply!!!
I guess the other reason to calm fish is so they return to a normal life sooner than later after being hooked and kept out of the water where breathing was a bit tough on the gills. The faster a fish overcomes the shock of being caught (and seeing my ugly puss), the more able it is to avoid predators and feed normally.
 
I have caught many fish over the year that were caught before, evidenced by torn lips and one that even had a small lure still stuck in its mouth. (Poor idiots.) None had sores or evidence of disease caused by a dry-hand release.