Van Gorder advises beginning fish farmers to start small — no more than 100 fish the first few seasons. Once you master a few basics, “you will be able to raise several species of fish in tanks, indoors or out, throughout the year,” he says.
In the Waianae cooperative, for example, a few aboveground tanks can produce more than 300 pounds of golden tilapia every six months.
Types of Aquaculture Systems
Here are the four aquaculture systems Van Gorder describes:
Cage Culture. This aquaculture method “provides the simplest means of growing fish if you have access to a pond,” Van Gorder says. He estimates a cage system could be built for about $100. “The only cost is for cage materials, fish and feed.”
In this system, a cage or pen made of plastic pipe and rigid netting is moored in any suitable body of water — a pond, lake, stream or millrace — and stocked with fingerlings that are fed until they reach a harvestable size.
“If you have a farm pond, building a floating cage will provide enough fish to feed your family year-round,” Van Gorder says. Channel catfish is the most common fish grown in cages; tilapia, trout, salmon and hybrid striped bass are other options.
Flow-through. This method diverts a continuous source of cold water, such as a stream, spring or river, into “raceways” that hold fish. Even a small volume of water can create a more productive system than a closed setup. “With just a few gallons of spring water, you can grow trout year-round,” Van Gorder says.
Like cage culture, flow-through systems are simple and relatively inexpensive, unless you don’t have access to a natural source of flowing water. It’s also important to note that flow-through systems are subject to regulations regarding the diversion and use of natural water sources. Be sure to talk with local fish and soil conservation authorities before making use of nearby streams.
Greenhouse Aquaponics. Within some form of greenhouse, this method uses a variety of plants — instead of filters to improve the water quality for fish. In addition to tilapia, trout, catfish or hybrid striped bass, you can grow different vegetables — including tomatoes, lettuce and cucumbers — as you would in conventional hydroponics. However, because fish are living in the water, the nutrient sources for greenhouse aquaponics must be totally organic; no herbicides, insecticides or fungicides can be used.
Greenhouse aquaponics is the most complicated aquaculture method, requiring a high level of management and components such as a water pump and aerator. Backyard fish farmers often combine aquaponics with a home recirculating setup (discussed later in this article). Altogether, such a system could cost up to $1,000, but using recycled materials can bring that price down significantly.
Home Recirculating. This is the answer for would-be fish farmers whose only water source is a garden hose. The best way to create this miniature fish farm is to use an aboveground vinyl-lined swimming pool in a back yard, garage or basement. The cost of such pools varies based on size, ranging from $300 to more than $2,000. They are durable, with only the vinyl liner needing replacement every few years.
For the ideal home recirculating system, Van Gorder recommends a pool 12 feet in diameter and 3 feet high. This size will hold about 2,000 gallons of water when filled to within 8 inches of the top. Unfiltered, that amount of water can produce only 10 to 15 pounds of fish, even with added aeration. But by controlling temperature, removing ammonia and waste, and oxygenating the water, that same amount of water can produce more than 100 pounds of fish in one growing season. Species best-suited to this system include tilapia, catfish, bass, carp and trout.
Because the fish spend all their lives in the same water, maintaining its quality is essential. Water must be clean, kept at the correct temperature and contain enough oxygen. Smaller pools have less margin for error and require even more management. Components of the home recirculating system include:
Solar dome. This is an inexpensive plastic cover that looks like a giant shower cap. Most of the fish recommended for backyard fish farming are warm-water species, which grow best at water temperatures above 80 degrees. In temperate climates, aboveground pools will reach about 70 degrees for only the warmest 12 weeks. But a solar dome will increase the average water temperature to about 80 degrees for at least 20 weeks.
Drum clarifier. This provides a simple way to collect and remove almost all of the organic material that accumulates in the water. Using siphons and a water or air pump, water flows between the pool and two 55-gallon drums that are filled with plastic mesh (orchard netting), which traps the solids.
Biofilter. This simple water wheel removes toxic ammonia from the water. It can be made with PVC pipe, corrugated fiberglass roofing and a few other materials available from your local home improvement store.
Aerator. An air pump or aerator adds oxygen to the water, which is necessary to raise healthy fish.
Emergency power. To keep aeration and pump devices running during blackouts, it’s a good idea to connect the system to a generator; or connect a simple 12-volt agitator to a car battery. Water quality won’t suffer if filtration and clarification are cut off for a few hours, but oxygen levels will rapidly fall if there are many fish in the pool.
Stocking Your Water Garden
Once you decide which system makes the most sense for your circumstances, the next big decision is which fish to raise.
“With an eye toward ‘sustainable aquaculture,’ whenever possible the small-scale fish farmer should utilize those species whose nutritional requirements are more easily met because they feed low on the food chain,” Van Gorder says. Feed pellets for catfish, for example, rely on soybean meal. More than 1 pound of fish can be raised from 1 pound of dry pellets. Carnivorous fish — trout, salmon and striped bass — occupy a higher place on the food chain. It takes 3 to 5 pounds of wild-caught fish to make enough fish meal for pellets that will produce 1 pound of cultured, carnivorous fish.
Here are descriptions of your best options among warm-water species — tilapia, catfish, carp and bass and — cool-water species trout, salmon and perch.
Tilapia. Tastes great and is one of the easiest fish to raise. Tilapia tolerate a wide variety of water conditions, including low oxygen levels and high concentrations of ammonia, and are resistant to diseases and parasites. Tilapia grow quickly under proper conditions — water temperatures of 64 to 90 degrees, with 84 degrees being optimal. Water temperatures less than 50 degrees are fatal. Java, blue and nile tilapia are the best species for backyard fish farming.
Catfish. Exceptional taste and hardy resistance to disease and parasites make catfish another good choice for beginning fish farmers. Catfish grow quickly — a large fingerling can reach 1 pound within five months. Channel catfish is your best bet; brown, black or yellow bullhead catfish are other options.
Carp. Traditionally unpopular for eating, carp from backyard aquaculture might surprise you. When cultured in clean water and prepared properly, it can taste excellent, Van Gorder says. Carp are hardy, resistant to disease and adjust to varying water conditions. Carp tolerate water temperatures from 70 to 90 degrees, but grow best between 80 and 85 degrees. Common, grass, bighead or silver carp can coexist in one aquaculture system.
Bass. The best species is hybrid striped bass, which has an excellent mild taste, even more so than wild bass. Bass is well-suited to cages and recirculating systems, but is more difficult to culture than tilapia, carp or catfish. Fingerlings require attentive care — they do not react well to poor nutrition, rough handling or bright lighting. Large and small individuals must be kept separately. Optimal water temperature is 80 degrees, but bass will tolerate 65 to 85 degrees.
Trout and Salmon. Two of the more flavorful fish, trout and salmon require much more precise conditions than warm-water species; control of water temperature is the primary factor. They require water temperatures between 55 and 60 degrees; rainbow trout can tolerate up to 70 degrees with careful management of oxygen levels. These fish can be stocked together and grow quickly, providing harvestable fish in one season. Best species are rainbow or brook trout and coho or Atlantic salmon.
Perch. The yellow perch is popular for its taste, especially in Canada and the northern United States. It grows best in water temperatures between 68 and 74 degrees. Yellow perch eat trout feed and can grow to a harvestable size — a third of a pound — in one season.
Fish Farming Resources
Getting Food From Water: A Guide to Backyard Aquaculture
By Gene Logsdon
On – By George DeVault