and that s one reason why a research project in switzerland is asking this question. how do fish fare in captivity they probably feel better when they have a good diet but how to tell if that is the case these are carp omnivores who need a regular supply of protein. other things one ready source of protein that could perhaps be used in aqua culture is duckweed. linda children is a doctoral student at the zurich university of applied sciences and her focus is fish welfare. she sing if carp like to eat duckweed and how well they can digest it. the logic is. all to quality and nutrition are 2 key issues for fish welfare if they re not getting the right kind of food they can t be doing well. so. whether or not duck weed is good for