It's well established that fish feel pain[0]. It's also possible to kill them far more humanely that we do now, e.g. by electroshock or by eugenol anesthesia. Despite this, out of the 1+ trillion fish killed by humans every year, almost all of them die slowly and painfully. We choose to do this simply because it's more convenient. Why would aliens treat humans any differently?
Intentionally signaling to aliens is one of the stupidest ideas I can think of. The Killing Star by Charles Pellegrino and George Zebrowski has a good analogy (longer quote here: http://www.projectrho.com/public_html/rocket/aliencontact.ph... ), describing a thought experiment of surviving the night in a crime-ridden Central Park:
"How do you survive the night? The last thing you want to do is shout, "I'm here!" The next to last thing you want to do is reply to someone who shouts, "I'm a friend!"
What you would like to do is find a policeman, or get out of the park. But you don't want to make noise or move towards a light where you might be spotted, and it is difficult to find either a policeman or your way out without making yourself known. Your safest option is to hunker down and wait for daylight, then safely walk out.
There are, of course, a few obvious differences between Central Park and the universe.
There's no obvious reason why aliens should perceive humans as either a threat or a resource. There may be non-obvious reasons, or they may be irrational about it. But unless interstellar travel is a lot easier than we think it is, it's unlikely that aliens would assume visitation is likely in either direction.
Humans cherish their pets. Aliens will cherish humans. Can intelligent life however leave things that they know about alone to do as it wishes without any interference whatsoever? No. In the short term maybe, but in the long term it's impossible. Why? Because either it's under control or it's a threat. Either you are a beast, in which case you become a beast of burden. Or you a barbarian, in which case you should be subdued. Or you are an ally in which case you must be integrated. Or you are food which must be farmed and eaten.
Heck maybe in the long run aliens have more to fear from humans than humans have to fear from aliens. But it's not going to end well for one of them in the long run.
Intentionally signaling to aliens is one of the stupidest ideas I can think of. The Killing Star by Charles Pellegrino and George Zebrowski has a good analogy (longer quote here: http://www.projectrho.com/public_html/rocket/aliencontact.ph... ), describing a thought experiment of surviving the night in a crime-ridden Central Park:
"How do you survive the night? The last thing you want to do is shout, "I'm here!" The next to last thing you want to do is reply to someone who shouts, "I'm a friend!"
What you would like to do is find a policeman, or get out of the park. But you don't want to make noise or move towards a light where you might be spotted, and it is difficult to find either a policeman or your way out without making yourself known. Your safest option is to hunker down and wait for daylight, then safely walk out.
There are, of course, a few obvious differences between Central Park and the universe.
There is no policeman.
There is no way out.
And the night never ends."
[0] https://www.hakaimagazine.com/features/fish-feel-pain-now-wh...