They have worldwide experiments with tilipia/duckweed farms. Mainly in undeveloped countries. They eat so much you have to have it farmed somewhere else and bring more in. Many universities are experimenting with it for numerous applications, sewage treatment, poultry food and tilipia farms. All are meeting with very high success rates. Not going to cure world hunger, but help out. Tilipia will finish off a complete pond of duckweed with proper stocking ratios. Grass carp won't. They just are not great surface feeders.