Here is a drawing of an ecofishery.
Fish farms have an issue with their waste piling up when the fish grow out from the hatchery. Feeding them antibiotics is unhealthy both for the fish and for the consumers. There is a more natural solution.
We propose a flexible enclosure in which water is filtered through aerobic bacteria. As the bacteria digest the waste it becomes inert, and serves as manure for sea plants. The plants are fed to herbivorous (vegetarian) fish.
These fish when they mature are fed to predatory (carnivorous) salmon. As a result, this ecological fish farm can market a healthier, safer food.