People should never dogpile – but the issues are real, not fringe.
They ARE only fish, but Trout are surprisingly fragile – I have definitely killed a few by accident, even following best practices. I NEVER fish for them anymore without a net – I know I will still kill a few now and then, but no more from improper physical contact with skin, ground, or anything else. I cringe when I think back to the way I released the saltwater fish of my misspent youth. They are far, far tougher, and I had to unlearn a lot of bad habits when I started fishing for trout. Lots of trout also die 12-24 hours later from lactic acid buildup if they are over-stressed or they are caught when the water is too warm. All due to oxygen deprivation and their own unique physiology. I think Gregs rule about holding YOUR breath is actually over-generous to the fisherman.
On the one hand parr like the one pictured are not my main concern – they might have been just dumped in there from a hatchery. But it makes me especially sad (yes, sometime angry too) to see much older fish treated without respect and care. On the other the parrs are even MORE fragile. No part of their body should be exposed to ANYTHING other than a net or a pre-wetted hand – otherwise likely subsequent death – another factoid about trout is that they have a protective film of "slime" on their body that a single exposure to a dry hand can remove, leading to a high probability of death later. No recriminations at all – just educational material that you may or may not know – but need to know. I'd say when fishing with a young person this is all the more important to keep in the forefront and explain to them. It is possible to be a fisherman and still love and respect the fish. Please, no more "still life trout on rock pictures". This is a no brainer if you know the risk factors.
For better or worse, nowadays serious fly fisherman that care about the fish have a secret code and will be evaluating your seriousness about the environment and taking care of the fish, and yes, even the more abstract idea of respect, by looking at your pictures, and, though you may not notice it, cringing and grumbling behind you back (and maybe occasionally to your face) when they witness obviously poor treatment. It goes something like this – in the picture it should look like you just barely lifted the fish out of the water briefly to take a picture (what you should ideally have actually done). A parr should be in a net or hanging in the water since they are super fragile. People who want use their rod as a measuring stick (a popular convention) should cradle it across their forearm. If the fish is big, one hand holds the tail and the other gently cradles the fish's midsection from below – no squeezing, a potential source of internal damage. Also the fish will actually flop around less by cradling as when you squeeze you put pressure on their main sensory apparatus along their sides. That, in addition to the fact that they are suffocating, is what make them freak out. My own pet peeve is the one-handed hero shot with a big fish that looks like it is getting its spine adjusted. If it looks like you laid it on the ground just to take a picture, you may impress your non-fishing friends by the beauty of the scene, but people in the know are naturally going to have negative reactions. Response to various "offenses" will range from thinking you are a careless noob (laying the fish on the ground), to being a total douchbag (gilling the fish) depending on the severity of the "offense". Generally the bigger/older the fish the more intense the reastion. Serious trout bums have been know to eviscerate people on social media for such "offenses". Not saying it is right, just wanted to make sure you know both the reasons, and that this is a "thing".
FWIW I have myself committed most of these offenses in the past, and still do on occasion when I am not paying attention, or spaz out in excitement of landing a particularly spectacular fish. Just ideals to keep in mind.
Here is a key. Custom Spey Rod guru Bob Meiser (perfect)

good ways to do parr pics.


Good


OY! My Spine!
Douchebag – unless the fish is already dead.
For fish like bass (not trout) that have a tough lower jaw lifting them up by the lower lip for a picture is considered just fine.

