We went to Japan in 06' to meet my wife's parents and let them meet their grandson, and while we were there visited some of the koi ponds and temples with these ancient ponds. Absolutely incredible to see in person and the various types of koi were breathtaking. Selling koi internationally is also a big industry over there as well with some fish selling for thousands or more.
In regards to craws and Japan, I am sure that they like to eat them as well. Just little biddy freshwater lobsters. However, I am sure that like here, there's a collector's and hobbyist trade for crayfish over there as well. Lots of various species with great coloration to be had.
Yeah, the world IS filled with crazy hobbyists. I am one of them. I collect those colorful glass baubles that adorned the telegraph poles along railroads, highways and city streets. I have climbed and cut down many abandoned poles to get the old glass insulators off of them, and what's surprising is, that some of these pieces of utilitarian glass sell for $30,000 or more! I sold two red-amber Whitall Tatum insulators back in 2008 for $11,000. I paid $3,500 for the pair. But I also knew that they were rare experimental pieces too.
I think ALL hobbyists are a bit crazy....