Invited Talk: Sustainable Use of Resources: Production of Food Waste-Based Feeds for Fish Culture

There is about 3,648 tonnes per day of food waste generated in Hong Kong and most of them still end up in our overloaded landfill sites. This is not sustainable as dumping food waste into landfill sites will definitely shorten the lifespan of existing landfill sites. Recycling of food waste as a source of protein to replace part of the fishmeal in commercial fish feed for culturing fish is an alternative way to reuse food waste which could partially ease the disposal pressure. In our studies, a polyculture culture set up was used to grow low trophic level fish, including a filter feeder (bighead, Aristichthys nobilis), a herbivore (grass carp, Ctenopharyngodon idellus) and a bottom feeder (mud carp, Cirrhina molitorella), with lower nutritional requirements. The results of the half-year field trial showed that grass carp and bighead carp fed by food waste-based diets were relatively free of mercury and polycyclic aromatic hydrocarbons (PAHs), compared with those fed with the commercial diets, containing fish meal. Furthermore, food waste-based diets were used for culturing jade perch (Scortum barcoo) and Nile tilapia (Oreochromis niloticus) in a fish pond for half a year. Health risk assessments based on the concentrations and of metal/loids (arsenic, cadmium, chromium, copper, mercury, lead and zinc) and PAHs in fish meat showed that the culture fish were safe for human consumption. This demonstrated that food waste possesses a high potential as protein source to substitute part of fish meal commonly used in fish feed for sustainable fish farming.