Racing to finish Mollisons 'Permaculture - a designers manual'. Im on the aquaculture chapter having skipped the 'dry' and 'cold' climate sections (they are worth reading for the principles but are not directly applicable to Akl). Polyculture ponds produce between 4 and 20 times as much food as monoculture agriculture at half the food input requirement of chicken and a fraction of that of beef. More imporantly ponds can be integrated into permaculture systems to add a further dimension of synergy and diversity. Therefore monoculture aquaculture (prawns, salmon) makes the same mistake as monoculture agriculture and consequently suffers from the same problems (disease, environmental degradation).