I'd like to respond to your "rant" hopefully with some enlightening information
As some on here know, I have been a part of the fish hobby and fish biz for a long time so sadly, I HAVE seen some of the changes that have taken place.
First off, Kudos to you for even thinking about this subject. The "ethical" hobbyist is not often heard from.
I'd also like to follow that with that this discussion is not about how the fish and animals being discussed got here on Earth. How you believe they got here is your opinion so please don't PM me trying to "correct" what I think.
Okay, to the meat of the subject:
There really needs to be 3 sides to this coin: the hobbyist side, the business side and the human side as they all are interconnected.
Let's start with the Human side. Mankind, for as long as there have been records, have kept wild animals as pets. For example, recent discussions flood my TV screen on the development of dogs. Whether we domesticated the wolf or not, dogs are genetically linked to them so without wolves, there would be no domestic dogs that we keep today. (My parents were dog breeders when I was just a little guy.) I recently looked at a poster of dog species and was amazed. Almost 50% of the types didn't even exist 25 years ago. They are the new creations to go along with man's needs for companionship.
Now let's dig into the "dark side" of the human race. Forests are being destroyed for the lumber to build things like houses, furniture and paper and anything else you need lumber for because man has over populated the planet. We are the only specie that lives above it's local environmental capacities. When we run out of our local resource, we look elsewhere for it to get it perpetuating the "need" for someone to take that tree down and do something with it. THEN, we have the food issue. How much if the Amazon forest was destroyed to become grazing land for cattle for export and crop land for soy beans for China? The answer will upset a lot of you here. The consequences of some of this was habitat destruction where the fish lived. And this is just one example. The country of Haiti was exploited and deforested which in turn let so much of it's land wash away after major storms that the reefs that encircled the island were destroyed. The pic of this from above was devastating to me as I was effected directly by this event. Again, this is just a small sampling of the effect that humans are having on the planet not just the livestock on the planet.
Next let's visit the business aspect of this coin: The fish business has come a long way since it's humble beginnings umpty ump years ago. Believe it or not, most of the freshwater fish you see in a pet shop are not wild fish. Probably only 25% maybe are wild stock. How do I know? Because most of the fish colors I see in stores don't exist in the wild. Let's start with the basic Guppy. If you see a really pretty single colored or Delta tailed Guppy, it was man made, not wild. Swordtails, if they aren't green montezumas, they are man made. Mollies, Not Green sailfin or Black sailfin, Man made. Angelfish, not Silver= not wild. Discus, Holy crap, I don;t think anyone even carries wild Discus anymore. lol ( J.K., I know some stores do but not that many.) The business of fish keeping has created the need to come up with "new" fish to keep customers coming back and these are not coming out of the rivers and streams and lakes so no problems with them. Right? Have you seen the Glofish? I don;t look kindly on this behavior but I understand it's creation. Albino fish, while the albino gene is a natural gene, there is a reason why you don't see many adult albino animals in the wild as this mutation makes them stand out against their background making them easier targets as food when young. There is a reason why the animals have the shapes and color patterns they naturally have. It's for their survival. So again, keeping the albino varieties is having no impact on the wild stock.
Let's get to the saltwater side, whether you subscribe to global warming/global climate change being man made or a natural event, the fact is that the earth is warming and it is effecting the inhabitants of both it's oceans and it's land. But the reefs are not just dying from this event. Pollution as well as overfishing of the basic food link in the chain are having more devastating effects than the "few" fish we take for our fish tanks. If you look at the effect that shark finning has had to the reefs, it far exceeds the reduction of fish stock due to collection for the hobby. And for what, SOUP? When the top predator is removed, the other members of the reef can have population explosions that actually kill the reef more than help it. So maybe collecting wild fish is not as bad as first thought? There are now over 35 species of fish that are being tank bred and most of them are perfectly suitable for the "nano" tank craze so again, these fish are not depleting the wild stock. Back in the 70s and 80s, I wouldn't recommend a saltwater tank to a customer that was less than 55 gals. The smaller tanks were just too difficult to keep fish alive in unless you had experience already ( which most people didn't back then.) A few of us also thought about the fact that most of the fish we were keeping in tanks would eventually have to be released or transplanted elsewhere as nobody was keeping huge tanks for fully grown Tangs, Angels, Groupers, etc back then except for marine parks like the Miami Seaquarium or Sea World type places. Now, you see homes with huge tanks thanks to shows like Tanked and Fish Tank Kings. ( 2 shows I don't watch often. BTW ) So the progression of buying a fish with the expectation of buying another tank for the fish as it grows is alive and well in the fish business. THAT has been going on since I was a kid. You bought a tank and fish that would outgrow it so that you would be forced to get another tank so you would have an empty tank that needed more fish in it..... etc. It was a business plan I suppose and it worked as it's still going on today.
But there's a dark side to the fish business as well. The opening of areas not available when I was in the importing business, have led to new fish discoveries which the "hobby" was primed for. But the dark side of human nature and the fish biz has already destroyed some of the stocks of these new fish. Celestrial pearl danios as well as many of the fish from Burma ( I'm old school. My books all call it Burma. lol ) as well as some of the rainbowfishes for example are in sever decline in their natural habitat due to the demand for these new fish coupled with habitat destruction. Once breeding programs get going, the need to collect them will be diminished and hopefully, it won't be too late when that happens. When was the last time you saw a wild barb or gourami, oscar, livebearer, etc. being sold in a store? The same will hopefully happen with these fish as well.
Okay, before this post gets way too long, the Hobbyist side:
As hobbyists, we hold a different look at things in the natural world. For starters, we can't just put water in a container and put fish in it and expect them to live. Opposed to just somebody looking to have a fish tank as an ornament, ( they are not hobbyists in my eyes) a hobbyist will learn about the water the fish come from, the natural tendencies of the fish as well as the proper decor the fish likes to live in as well as the foods it prefers to eat. All the things necessary to keep our pet healthy. Just because a fish we keep is tank bred and raised, it has the wild genetics of the fish which controls it's likes and dislikes. That part doesn't change. Whether in Freshwater or Saltwater, the hobby, and it's hobbyists, have played a continual role in the understanding of how the natural world works. Now, because of this new understanding, there has been mention in a number of programs I have seen of how the aquarium hobby may be the future of the wild stocks of fish and corals should natural occurrences destroy the wild stocks. Coral fragging was in it's infancy when I left the fish biz for a while. Ken Nedimeyer was fragging local (Florida) corals in the keys and a number of the coral farms copied his procedures. ( His was still in the ocean.) And fish were being experimented with to see the fesability of breeding large Angelfish in land based fish farms. A man made cross between the French Angel and the Grey Angel was created through this effort. The end result, they produced too many babies for a land based hatchery. But today, there are some of the larger Angels being tank bred or raised so there's a thumbs up for the hobby. Which brings me to my last point, unlike most freshwater fish, marine fish can have thousands of eggs in a spawn. While certain fishes who are demersal spawners, may only have a couple hundred eggs and mouth brooding species may only have under 50 fry at a time, fish like the larger Angelfish have approx. 300,000 eggs per spawn with butterfly fish having 50,000 to 100,000 eggs per spawn. These are paired fishes. With Tangs, which are schooling spawners, who knows how many eggs are being released per spawning? Years ago, I attended a lecture by the then head of the Rosensteil School for marine science ( part of the university of Miami) who said that "if we protected 20% of the world's reefs from any human activity, the fish living on those reefs could produce enough offspring to populate 100% of the world's reefs." So that brings me to this question: Is keeping fish in a fish tank really unethical? I don;t think so. I think keeping a large fish in a small tank is unethical. I think not learning about the fish you keep is unethical. I think not doing everything necessary to give your fish or pet the best possible care you can is unethical. I think creating living "toys" is unethical. But I don't think just the act of keeping the fish in a container, suitable to it's needs, is unethical. That's my view.
Thanks for reading this whole thing.
I hope it helped.