Re ECF Project: 2009-37

Project Title: Integrated Pond Fish Farming using Food Processing Wastes: for Quality Fish Production and Habitat Conservation

Applicant: Prof. WONG Ming Hung of Hong Kong Baptist University

Total Approved Grant: $1,900,900

Duration: 3/1/2011 to 2/7/2014

Project Status/Remarks: Completed

The project aims to redevelop the local inland fishery industry in order to produce safe and quality fish products; and to promote recycling of food wastes. The objectives of the project are:

  • to conduct a field survey and desktop survey linked with AFCD’s database so as to update the status of local fish ponds;
  • to raise the overall fish yield, by enhancing the feed conversion and digestibility of food wastes used as fish feed, and by adding probiotics (e.g. baker yeast) and enzymes (papain and/or bromelain);
  • to produce safe and quality fish products by cultivating low-trophic level fish species in order to avoid biomagnification of certain persistent pollutants (i.e. pesticides and mercury) along the aquatic food chain; and
  • to validate the feasibility of restoring/reactivating some of the ponds for aquaculture, (by recycling food wastes as fish feeds), based on cost benefit analyses.

Summary of the Findings/Outcomes:
Growth performance & haematological parameters of grass carp and grey mullet could be improved by adding bromelain and papain to the food waste pellets, through enhancing feed protein solubility, feed utilization and conversion, leading to better fish growth. 1% and 2% mixture of bromelain and papain can enhance the feed conversion and elevate IgI & NBT levels. In addition, the feeds with baker’s yeast generally showed better feed conversion and growth rates than feeds without yeast. Nitroblue tetrazolium (NBT) activity in blood and bactericidal activity of plasma were stimulated by implementing yeast in feeds, and a stronger disease resistance to Aeromonas was achieved. The optimal dose was 2.5% yeast (S. cerevisiae) with an addition of bromelain and papain (FWA). The results indicated that food waste is able to provide the essential proteins and amino acids for fish with different feeding modes. Upon adding enzymes (bromelain and papain) and baker’s yeast into food waste, fish growth and immunity were further enhanced. On the other hand, the International Conference on Biological Waste as resource with a Focus on Food Wastewith a half-day symposium entitled “Local symposium on Food Waste as Fish Feed in Chinese” was successfully held on 1-3 Dec, 2014.