I am an aquaculturist by profession. Duckweed does best in full sun with lots of nutrients (N and P) and with minimal current. The 50% crude protein is on a dry weight basis, not wet weight. You will have to dry it down a lot and by live weight, it is close to 90% moisture.This has been on my wish list of things to try. I have three ponds on my property, two of which would be suitable for duckweed cultivation. Are you feeding fresh or drying and adding to the feed ration?