$curWeaInfo.name, $curWeaInfo.state
Current Conditions
0:$curWeaInfo.min AM $curWeaInfo.tz
Dew Point
$curWeaInfo.wdir at $curWeaInfo.wspd mph
$curWeaInfo.bar in. F
$curWeaInfo.visibility mi.
$dailyWea.get(0).sunrise a.m.
$dailyWea.get(0).sunset p.m.
7-Day Forecast
$dailyWea.get($m).high°F / $dailyWea.get($m).low°F
$dailyWea.get($m).high°F / $dailyWea.get($m).low°F
$dailyWea.get($m).high°F / $dailyWea.get($m).low°F
$dailyWea.get($m).high°F / $dailyWea.get($m).low°F
$dailyWea.get($m).high°F / $dailyWea.get($m).low°F
$dailyWea.get($m).high°F / $dailyWea.get($m).low°F
$dailyWea.get($m).high°F / $dailyWea.get($m).low°F
Detailed Short Term Forecast
Issued at 0:$curWeaInfo.min AM $curWeaInfo.tz

Fish business caters to educational projects

April 4, 2013 | 0 comments

The question that R&D AquaFarms is built on is this - "have you tried to buy 50 tilapia fry lately?"

People who want to experiment with fish farming, or who have a school project where they need only a small number of these popular warm-water fish are generally out of luck if they call most fish suppliers, says Shawn Ristow, one of the partners in the business.

His rural Oshkosh business caters to these buyers who want a small number of fish. Most of his company's "fry", as the little fish are called, go to FFA chapters where members want to start aquaculture projects or to other school groups that want to experiment with commercial rather than ornamental fish.

He started his business with a buddy 12 years ago and knows firsthand what it's like to get laughed at on the phone when trying to buy fish to get started. They wanted to try their hand at raising tilapia, but didn't want to invest in huge systems at first.

"We wanted to try it and see if we liked the taste of tilapia first of all. We wanted to make sure we were raising something that tasted good."

Tilapia are native to Africa and South America and don't do well if water temperatures get too cold, so in Wisconsin's climate they must be raised indoors. Ristow experimented with different kinds of systems.

At first he raised tilapia in a "pond" lined with an old waterbed mattress and heated the water with wood to save money in some of his early experiments.

When the system really got rolling was when the fish rearing was matched up with plant production - what those in his business call "aquaponics" - a combination of aquaculture and hydroponics.

In these combined systems the water from the fish tanks is circulated through beds where plants can get nutrients by utilizing the fish waste. When the water is returned to the fish tank from the plant beds, it has been filtered by the plants.

He showed these aquaponic systems to members of the Wisconsin Agribusiness Council last week when they toured the business.

There was a learning curve on these types of systems, Ristow says. "We were using cherry tomato plants and the plants were huge but we had no tomatoes. I was trying to puzzle that out when I realized there were no pollinators inside our building.

"So after that I was in there pollinating the plants every day and then we got tons of tomatoes."

Ristow and his partner in the business, Pete Yost, recently began designing their own small systems that customers can purchase so they can experiment with fish production and even aquaponics if they want to. Some of their smaller systems are small enough to fit on a tabletop.

Ristow and Yost built their business on catering to high schools across Wisconsin, and especially FFA chapters that want a small-scale system. Today they get calls daily from customers coast to coast.

One of the challenges to their business has been finding the proper shipping method for 10, 15, 25 or 50 small fry. "We've got to get them there overnight," Ristow said.


Another challenge is that fish will grow at different rates, even when they start out the same size. "One of the continuing projects is to take the 'pigs' out and put them with bigger fish," Ristow said

Yost and Ristow do this "sizing" of fish every week. When tilapia are two years old they can be as large as 15 inches and weigh 2 ½ pounds.

Tilapia, it turns out, are great fish for school projects because they can grow to a harvestable size during a school year. At the end of the project the students can have a fish fry, Ristow says.

"They can go from fry to nine inches or 1 ½ pounds in nine months. If they have more time they can get a lot bigger."

"It fits perfectly for a school project," said Yost. "They can start out in September with two-inch fish and by May they are 1 ½ pounds."

Back when the business was getting started, Ristow went to the Wisconsin Aquaculture Association. At that time he found that there wasn't much interest in growing the warm-water tilapia. "Everybody was interested in trout and perch and nobody had experience with the warm-water fish."

Since that time Wisconsin has sprouted some larger fish farms with tilapia and many of them also incorporate the idea of growing plants to feed off the fish tank waste. Ristow said one farm he has seen uses "rafts" of the pink rigid foam insulation with small holes in it to hold the seedlings.

The four-by-eight-foot sheets of insulation cover the water, helping to prevent algae from growing in the ponds. The roots extend downward and can feed off the nutrient-rich water.

"Some producers tell me they have the fish just to keep their produce business going. If they can sell fresh lettuce to the Twin Cities all winter long, that's their business model."

Ristow said he often counsels schools to put their fish in one room and their plant beds in the nearby greenhouse. That way the fish can stay warmer and the plants thrive in the light of the greenhouse.

That's the kind of system they helped design at Oskhosh West High School. The fish tank is inside and a new greenhouse holds the aquaponics part of the system.

Tilapia are happiest in water that's 85 degrees. If water gets as cool as 70 degrees they will begin to feel stressed. "When water gets down to 50 degrees tilapia will go belly up," Ristow said.

As long as they are given the proper conditions, he said, tilapia are pretty resilient fish. When excited they can flip themselves right out of their tanks and often can survive that if they are put back in the water.


One of the challenges of raising tilapia in a cold climate like Wisconsin is of course keeping the water warm. Yost said some fish farmers have gotten creative about how they heat water.

A farm in the Dakotas has access to hot springs and uses that naturally warm water to raise tilapia.

One of Ristow's ideas was to partner with an ethanol plant to create a system where the fish use the warm process water from that system. So far he hasn't gotten that off the ground, but he's always thinking about new ways to get the job done.

Tilapia can tolerate conditions of significant crowding if the water is the right temperature and if there is a good enough filtering system. Ristow recommends pea-gravel growing beds for plants. He has devised and used them for years and finds they work well.

"The plants and the fish are totally dependent on each other," he said.

Ristow and Yost said they would estimate that their customers have about an 85 percent success rate. "We run the gamut from people telling us 'every fish was great' to a call that says they need more fish," Yost said.

They said that anyone who is planning to raise this kind of fish on a large scale needs to have systems that provide for emergencies. "If the power goes out you need to have systems that will kick in even when you're not around."

Ristow said tilapia don't need as much protein as carnivorous fish like trout. In their native waters they feed on plants.

In the aquaponic systems if there are plant roots that extend into the water, the fish will eat them, he said.

All the fish they sell out of their Oshkosh facility are males that are a hybrid of Mossambica and Hornorum tilapia. They have been bred to achieve fast growth and good fillet size.

Ristow and Yost strive to remove all the females because if they are in the tanks with the predominantly male population, the fish will "get crazy" and fight with each other.

Twelve years ago Ristow said he was the only one doing this kind of business and educational projects were his primary focus. Next year he plans to pursue the market of homeowners who want to try their hand at fish farming in a small way.

"Tilapia are getting so popular now and there is a growing interest in fresh-harvested, locally grown fish. These fish produce a delicious firm, fine white flesh with a mild taste," Ristow said.

Next year's project for R&D AquaFarms may also be a new facility. The business is outgrowing the current facility - a building that has been retrofitted for several uses over the years including bait shop, hair salon and motorcycle repair shop.

Ristow said they are still kicking around the idea of a new facility, perhaps at his home. Whatever they build, it will be well-insulated to keep his favorite fish warm.

For more information see their website: www.rdaquafarms.com.

This site uses Facebook comments to make it easier for you to contribute. If you see a comment you would like to flag for spam or abuse, click the "x" in the upper right of it. By posting, you agree to our Terms of Use.

Page Tools