Fish Fry with a Side of Salad | Ohio Sea Grant

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Fish Fry with a Side of Salad

12:00 pm, Tue February 13, 2024 – A new recirculating aquaponics system, capable of raising Lake Erie fish and crops like lettuce and tomatoes at the same time, might be the key to the future of aquaculture in the Midwest

Fish with a side of salad, please.

While you might assume these foods come from different places, Ohio Sea Grant researchers could tell you that the whole meal could be produced at an aquaculture facility near you.

Researchers Dr. Kevin Neves and Dr. Silvia Newell recently showed that a recirculating aquaponics system is more than capable of simultaneously raising Lake Erie yellow perch and crops like tomatoes and lettuce. Through what’s known as integrated multitrophic aquaculture, or IMTA, the system might be the key to the future of aquaculture in the Midwest.

“Simply put, it’s organisms working together to utilize the byproducts of each other,” said Neves, associate teaching professor in Bowling Green’s Department of Biological Sciences, who first started developing the demonstration system at the university’s Biology Greenhouse in 2016 to show the feasibility of recirculating aquaculture in the Midwest.

Learn more about this Ohio Sea Grant research.

The system houses three large tanks, two filled with yellow perch and one filled with crayfish or prawns. Water from the tanks flows into a 5-by-20-foot raceway that supports plants on floating discs, with roots submerged underwater.

“The uneaten fish food and feces gets collected and fed to our crayfish, who excrete nutrients like nitrogen,” Neves explained. “The water continues to recirculate throughout the system so that the plants are continuously taking up nitrogen, and the organisms are producing it.”

a greenhouse with large tomato plants and tanks filled with water

In the recirculating aquaponics system, water flows between tanks with yellow perch and crayfish and a raceway with floating boards that support tomato plants.

Early on, researchers were concerned about levels of dissolved nitrogen in the system, as certain forms of nitrogen can become toxic to fish at high levels. That’s why Newell, then an associate professor of earth and environmental sciences at Wright State University, joined the project to study nitrogen cycling.

“Ammonia, urea, and nitrite all at very high levels can become toxic, and if you have a recirculating system, that can be a concern,” said Newell, who is now the director of Michigan Sea Grant and a professor at the University of Michigan. “The system seemed to be in balance, so we wanted to measure the nitrogen dynamics and figure out how it was working.”

The system offers both economic and environmental benefits. While most aquaculture systems are monocultures, raising one fish species, IMTA systems house multiple organisms at different levels of the food web. This results in more outputs — fish, shellfish, produce — with the same amount of feed.

“Fish are a long-term crop. It’s a lot of investment, and it takes a long time before you get a payout,” Newell said. “Having these additional products in the meantime to help support your investment is really important financially.”

Another major advantage: the recirculating system produces no nutrient pollution. Unlike in traditional fish farms, water doesn’t leave the system, so there’s no risk of nutrients hindering surface water quality and contributing to the growth of harmful algal blooms.

“We’ve had incredible growth of the tomatoes, incredible growth of the fish, so it’s feasible. The Midwest is not known for its aquaculture, but there’s no reason that it shouldn’t be.”
Dr. Kevin Neves

“People seem to like this idea of having a lower nutrient output back into the environment and a more sustainable, socially acceptable, environmentally friendly product,” Neves said. “We’ve even seen that people are willing to pay a little extra once they know where this product is coming from.”

While multitrophic aquaculture had already proved successful in marine environments, Neves and Newell wanted to bring a Lake Erie focus to the concept. Their goal was to produce a “plug and play” model to demonstrate what such a system could feasibly grow in the Midwest.

Researchers regularly collected data from the greenhouse tanks, measuring rates of nitrogen cycling processes within the system. They aimed to find an optimal balance of nitrogen production and uptake for fish and crops.

a fish being held over a net

Blind taste tests conducted by Neves and fellow Bowling Green researcher Dr. Jonathan Kershaw found that the yellow perch produced in the aquaponics system was a comparable product to wild-caught fish.

Ultimately, Newell and Neves found that their system was successful. The balance was close to a steady state, with around 200 grams of nitrogen added and 200 grams converted to nitrate, the form that is best for plants.

“We were able to figure out how the nitrogen gets moved through the system and found that the rate at which ammonia was converted to nitrate — nitrification — was impressive,” Newell explained. “This conversion is important because nitrate is a form of nitrogen that is typically safe for most organisms, even at higher levels. And plants flourish with a lot of nitrate.”

Accordingly, the system had huge plant growth, with plants taking up 12 grams of nitrogen per month. In a span of six months, the researchers harvested 110 pounds of tomatoes and the system grew about 13 pounds of perch.

two large tomatoes on a vine

With no additional nutrients or energy required, a recirculating aquaponics system can make greenhouse tomato production more sustainable.

“We very much demonstrated that it is very feasible to develop a system that is simple to operate and doesn’t require a lot of technical expertise,” Neves said. “We’ve had incredible growth of the tomatoes, incredible growth of the fish, so it’s feasible. The Midwest is not known for its aquaculture, but there’s no reason that it shouldn’t be.”

Sustainable fisheries and aquaculture are an important part of Sea Grant’s mission, Newell said, and the pilot system has the potential to be used more widely across Great Lakes states. Sea Grant extension and education efforts can help connect farmers and producers expand aquaculture operations. Unfortunately, the startup costs for a recirculating system can be steep. The Bowling Green system was so successful in part because it relies on existing infrastructure — a greenhouse with electricity supplied by the university — that doesn’t require heat or light, just cooling for two months in summer, she said.

“There are a lot of opportunities for funding to help jumpstart aquaculture in the Midwest right now, and the more outreach we can do to explain and share information about it, the more successful we’ll be in supporting new ventures,” Newell said.

Meanwhile, Neves is studying consumer perception of food produced by the aquaponics system alongside Dr. Jonathan Kershaw, assistant professor in Bowling Green’s food and nutrition program, and Drs. Fei Weisstein and Jeffrey Meyer of the Schmidthorst College of Business. Researchers conducted taste tests to gauge consumers’ preferences and inform marketing strategies for aquaculture producers in the Midwest.

“This study has informed the direction that (Neves is) going with his research to try to make it more marketable to develop aquaculture in the region,” Newell said. “And as for me in my role at Sea Grant, it’s really helped me understand some of the barriers and challenges to expanding aquaculture across the Midwest.”

For more information about this research and creating aquaponics systems, contact Dr. Neves at and Dr. Newell at Watch more about this research in Neves and Newell’s Freshwater Science Webinar from December.

Ohio Sea Grant is supported by The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES) School of Environment and Natural Resources, Ohio State University Extension, and NOAA Sea Grant, a network of 34 Sea Grant programs nation-wide dedicated to the protection and sustainable use of marine and Great Lakes resources. Stone Laboratory is Ohio State’s island campus on Lake Erie and is the research, education, and outreach facility of Ohio Sea Grant and part of CFAES School of Environment and Natural Resources.

ARTICLE TITLE: Fish Fry with a Side of Salad PUBLISHED: 12:00 pm, Tue February 13, 2024
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Alex Meyer
Authored By: Alex Meyer