Freshwater Pond Technology
The ASA-IM defines 80:20 pond fish culture as the raising of fish crops in ponds where a single feed-taking species of a single size group composes approximately 80% of a total fish harvest weight, and one or more other "service", or non-feed-taking species, compose the other 20%. The “service” species could be filter feeders that feed on waste, or predators that control population in a pond with both genders that could reproduce. This technology, which is a modification of standard intensive pond monoculture, was developed in China and is mainly used in freshwater pond production.
Silver carp, a filter-feeding freshwater fish native to China, is typically used as the service species in an 80:20 system, as it does not compete for feed and has reasonable economic value in the marketplace.
A predatory species can also be used as a service species in 80:20 systems, such as to control tilapia reproduction where there is less than 100% all-male progeny.