ARS researcher and technician in Leetown remove
rainbow trout from fresh water fish tank for tissue samples. The fish are part
of a selective breeding program and require a continuous supply of high-quality
water. Click the image for more information about it.
New System Developed for Raising Fresh-Water Fish
January 25, 2005
A new system that treats, filters
and conserves water in fresh-water fish tanks has been developed by an
Agricultural Research Service scientist
and is being used at an ARS research facility in West Virginia.
The new system recirculates up to 90 percent of the water in two fish
culture bays at the ARS National Center for Cool and Cold Water Aquaculture (NCCCWA)
in Leetown, W.V.
ARS environmental engineer
Brazil custom-designed the system to support multiple rearing tanks, which
are connected to a centralized water filtration and treatment system similar to
that constructed by the Conservation
Fund's Fresh Water
Institute. The rainbow trout raised at the Leetown center are part of a
selective breeding program and require a continuous supply of high-quality
Brazil's design supports two culture bays. When the water leaves the bay's
fish tanks, it flows through a microscreen that removes fine particulate
matter, and then through a biofilter that removes lethal wastes like ammonia
and nitrites. In the next stage, carbon dioxide is removed from the water and
oxygen is added before the water enters a storage tank. Finally, the water is
treated with ultraviolet light for purification before returning to the fish
The system was designed to maintain water quality while recirculating up to
about 90 percent of the culture water. This helps with conservation, because
only 10 out of every 100 gallons of water used is fresh.
The system also cools the water to temperatures that rainbow trout need to
survive--ideally, around 55 degrees Fahrenheit. Recirculated water is generally
warmer than that, so chilling the fresh water as it's added reduces the
temperature. Adding this fresh water helps maintain high water quality.
Brazil's innovation has cut NCCCWA's demand for fresh water at a time when
fish culture activities have increased. As a result, NCCCWA is more efficient
at utilizing its water resources.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.