A great short article about carp/koi and their meanings and use in different countries.
AT FIRST GLANCE, there’s nothing especially appealing about carp. The gray-green bottom feeders trawl the muddy depths of freshwater rivers, lakes, and ponds all over Eastern Europe (in the United States, carp is considered an invasive species and rarely eaten). The fish are hardly an attractive symbol of wealth and prosperity. Yet, thanks in large part to dietary restrictions imposed by Catholicism, carp are a beloved presence at Christmas dinner, and their scales highly prized.
Carp as a good luck charm (matadornetwork.com)