We didn't normally replace the stuff in the display tanks. The fish in them did better than the stuff in the for sale tanks because they were in a well set up tank with plants and we didn't add new fish to the tank all the time. Most of the issues we had with sick fish were from newly imported fish that had diseases when sent to us.I know..Fish stores always have fish that ignore people. One reason might be that they replace fish that don't adapt.
In my opinion, most wild caught fishes are stronger than captive bred stock. They usually have fewer diseases/ parasites too. This comes down to the Asian breeders who feed the fish crap, or organisms grown in crap, and the fish are seriously inbred and genetically weak.
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Most videos are staged full stop. Even a lot of the BBC documentaries are made in giant sheds in the UK. I have a collection of fish documentaries from the 70s and early 80s and they were really cool back in the day. But nowadays I can see where they use fish in aquariums vs fish in the wild.I stick to my guns, most vids of adult Discus in planted aquariums are not grown out in that aquarium, they went in large.
Lots of videos on YouTube are staged, especially fish tanks with loads of plants and fish. People spend time setting it up, add a heap of fish, film it and then take it apart. It's all about ratings.