I saw a social media post that a European company recycled salmon skin to make shoes out of it. In Japan, our ancient time, people were eating fish head to tail, and it seemed to be the same way until recent time. I remember that I saw fish head and bones in meals at home in my childhood, and I was punished often at the dinner with my parents when I didn't eat meat around the bones, including skin. I didn't like fish because of that back then. Now I'm a chef, butchering and slicing fish as a daily routine. I cannot waste head and bones without making fish broth, or feeling very guilty. There became natural feeling to respect ingredients since I started working in restaurant kitchen. Some people say "ITADAKIMASU" shows the respect in Japanese culture, and it means that we will "take the life" of food ingredients with dignity. But I doubt that it was what it meant originally.
The grace, "ITADAKIMASU" before the meals, doesn't have any more than 100 years of history, appeared in a book first time in 1934 as long as I know. (Please let me know if it's not correct.) I believe that it started to teach their children a dining manner. The children must be respectful to persons who cook for them. In a daily life, "ITADAKIMASU" means "receiving" than "taking" (unless you were a samurai worrier), so it's gratitude to the provider. However, we tend to feel more than that, because the provider isn't only a person who cooks it for us, but also the ingredients itself. Japan has a unique culture and philosophy to connect between ourselves and other creatures' lives. And we feel "ITADAKIMASU" as our respect to that. If the word (ITADAKIMASU) is translated directly into English, it means "TAKE" (your life). But if we think about complete sentence, in this case, "Anata no inochi wo itadakimasu", it should mean "BORROW" (your life - to return our lives to the soil later) to be more accurate. So if we waste that, we don't take care of ourselves well and won't have enough "life" in us to go back to the soil when we die.
Cooking with fish head to tail requires more work, but well worth it.
ITADAKIMASU.
-Youji Iwakura