They say that a Trout lives in a gravity free environment.When a Trout is removed from the water that its insides can be harmed or even crushed just from the gravity induced on the fish
I've never heard that argument before, but I'm certain that it's 100% wrong. Being neutrally buoyant underwater like a trout is not the same as being weightless in outer space. In near Earth orbit in outer space, you're weightless because the force of gravity pulling you toward the Earth, and the centrifugal force pushing you away from the Earth, balance each other out, and both of them act on every single atom in your body. The difference for trout underwater is that gravity and the buoyant force
don't both act on every single atom directly. Gravity still pulls every atom down, but the buoyant force that balances it out only acts on the outside of the fish. So the fish is being held up
from the outside by water, just like it's held up from the outside when you pick it up in the air. The effect of gravity on its internal organs isn't any different in the air than underwater.
the damage to the Trouts skin when handled
It's certainly possible to damage a fish's skin and leave it more vulnerable to infections. That might be common for people who are really bad at handling fish, who have them flopping and tangled in the net for several minutes or banging around on the rocks, etc. But if you keep your hands wet, keep the fish in the water most of the time, and just lift it a few times for a quick unhooking or a couple photos, it'll be fine.
So many times I see people holding a Trout for a picture or photographed on the bank of the stream.I have done this myself and am not trying to judge anyone.I Have changed my C+R practice over the years and wonder how you all feel about this.
I don't think there's any science to justify a high level of paranoia about taking a picture or two of a fish. People just need to try to handle the fish carefully.