What are closed, ecycle or water reuse systems?
These are systems in which water is continuously circulated through fish tanks and then treated by various physical and biological processes so that it can be reused, or recycled, through the fish tanks again. Treatment processes include solids removal, aeration and biological filtration to oxidize excretory fish wastes in solution. Like pump ashore systems, they are also expensive to build and operate and they consume substantial amounts of energy. For some species, however, especially for the production of some juvenile fish, they offer the advantage of complete control over the rearing environment. But this is achieved at an energy and financial cost that is only justified where the value of the end product is high. For this reason they are not appropriate for producing fish, such as salmon, where the goal is to make it affordable to as many consumers as possible. Political efforts to legislate the use of on shore tank systems only for species like salmon would doom the industry to
