NASA Tournament Lab


Protecting the Natural Flavor of Catfish

Blue-green algae can cause off-flavors in farmed catfish, leading to costly harvesting delays. How can USDA-ARS eliminate these off-flavors?

Challenge Overview


The United States Department of Agriculture’s Agricultural Research Service (USDA-ARS) seeks to identify methods or technologies capable of reducing or eliminating instances of off-flavor in farmed catfish raised in ponds. The Protecting the Natural Flavor of Catfish Challenge will award a total prize purse of $60,000 for the most compelling approaches for preventing or eliminating these off-flavors which cost farmers millions of dollars each year. 


The Problem

Exposure to certain varieties of blue-green algae, also known as cyanobacteria, can cause undesirable changes to the flavor of farmed catfish. This off-flavor delays the harvest for roughly 50% of catfish ponds each year in the United States. Annually, this delay alone can cost catfish farmers millions of dollars in lost revenue and expenses to maintain the fish until flavor quality returns.

USDA-ARS scientists, as well as industry experts, have worked for decades to find new solutions for this problem. While methods to combat off-flavor in catfish have been identified, they are only partial solutions, requiring repeated treatments to reduce off-flavor occurrence, and providing no guarantee of successfully eliminating off flavors. Frequently, preventative treatments are not applied; when off-flavor is detected, harvesting of the pond is delayed as the farmer begins the treatment process and waits for flavor quality to be restored.


The Challenge Breakthrough

The USDA-ARS seeks to identify methods or technologies capable of reducing or eliminating instances of off-flavor in farmed catfish raised in ponds. Innovations that address pre-harvest management techniques or pre-/post-harvest treatments are of interest. Proposed approach must reduce off-flavors in catfish to a level that is undetectable to professional flavor testors.


What You Can Do To Cause A Breakthrough

  • Click ACCEPT CHALLENGE above to sign up for the challenge
  • Read the Challenge Guidelines to learn about the requirements and rules
  • Share this challenge on social media using the icons above. Show your friends, your family, or anyone you know who has a passion for discovery.
  • Start a conversation in our Forum to join the conversation, ask questions or connect with other innovators.

Challenge Guidelines


In the United States, nearly 400 million pounds of farm-raised Channel and Blue catfish are harvested annually, primarily in the Mississippi delta region. Prior to harvesting, sample fish are captured and tested to ensure high quality. One of the most important evaluations performed is taste. Professional food tasters briefly cook the fish in a microwave and taste it, without seasoning or other preparations, in order to evaluate the innate flavor of the fish.

Unfortunately, exposure to compounds from varieties of blue-green algae, or cyanobacteria, can cause unpleasant tastes in catfish, described by taste testers as “earthy” or “muddy”. If a sample fish is found to have these off-flavors, there are several options.  The pond can be left alone and fish retested after several months to see if flavor has improved, or the pond water must be treated to remove these algae before harvesting can proceed. Treatments can take weeks to months before they are fully effective at removing the off-flavor from the fish. Both approaches result in lengthy and costly harvest delays.

Research has identified several effective methods for treating affected catfish ponds but these methods are generally not implemented until an off-flavor fish is found. One potential method is to relocate the entire school of catfish to a new pond with water uncontaminated by blue-green algae. The downside to this, apart from the additional cost to the farmer, is the additional stress placed on the fish - stress which itself can impact the flavor and texture quality of the harvested fish. Another treatment method is the application of algicides like copper sulfate or diuron to the affected pond water. While effective, public perception of additional chemical usage can limit deployment, as can the potential for unintended consequences for the overall pond ecology.

A Global Aquaculture Alliance article estimates that US catfish farmers lose as much as $47M a year due to off-flavors.  Since additional costs caused by off-flavor can account for as much as 17% of total production costs, the development of new tools to help catfish farmers maintain the natural flavor of the catfish is critical.

USDA-ARS, working in conjunction with the farmed catfish industry, has researched this topic extensively and believes that input and insight from the global innovation community can positively impact this persistent problem.

USDA-ARS has identified three different points in the process where new methods or technologies could be implemented to address off-flavors in catfish:

  • Pre-harvest management practices: new methods/technologies that work to prevent the development of off-flavor causing blue-green algae in catfish ponds
  • Pre-harvest treatment technologies: new methods/technologies to remove off-flavor from catfish once it has been detected in sampled fish prior to harvest
  • Post-harvest treatment technologies: new methods/technologies that would allow processors to remove off-flavors from catfish after harvesting

Ideally, proposed approaches will meet the following performance criteria:

  • Reduce or mask off-flavor compounds to a level undetectable to professional flavor testers (~100ng/kg)
  • Cost the same or less than current treatments (currently ~$177/acre-ft, which translates to ~$8000 per pond. The average catfish pond is a 10-acre pond, 4 ft deep)
  • Maintain catfish well-being
  • Be neutrally or positively viewed by consumers
  • Environmentally safe for both pond and surrounding areas
  • Safe for operators and other personnel

USDA-ARS believes that exciting new technologies and innovations are possible and welcomes the global community to provide insight in all forms to this topic, regardless of approach.



ARS will award up to $60,000, to be split among the top-scoring and eligible submissions, with at least one prize winner in each category. Each prize awarded will be up to $30,000 and no less than $5,000.

  • Category 1: Pre-Harvest Management Practices
  • Category 2: Pre-Harvest Treatment Technologies
  • Category 3: Post-Harvest Treatment Technologies

Furthermore, it is the intention of ARS to facilitate the implementation of new technologies in the field to the benefit of the industry. To that end, ARS will consider post-challenge discussions between ARS scientists and winners, engaging with winners in joint publication efforts or in collaborative work to further develop proposed technologies. The USDA-ARS Office of Technology Transfer will assist with cooperative research agreement options as warranted.



Open to submissions              August 20, 2020

Submission deadline               December 15, 2020 @ 5pm ET

Judging                                           December 15, 2020 - February 23, 2021

Winners                                         Announced March 2, 2021


How do I win?

To qualify for an award, your proposal must, at a minimum:

  • Prevent, eliminate, or mask off-flavor in farmed catfish
  • Have supporting data, or a strong scientific rationale
  • Be safe for the fish, the environment, and users


Judging Criteria

Section DescriptionOverall Weight
Impact on Off-Flavor: Describe the impact your technology has on off-flavors. Does the proposed approach provide for a positive impact on off-flavors?25
Innovation: Describe how your technology is different from the competition/alternatives. Does the proposed approach use a novel technology or an existing technology used in a novel way?20
Evidence: Describe the evidence to support the efficacy of your approach. Do the presented data and/or scientific rationale support the claims of elimination of off-flavors in farmed catfish? 20
Environmental Impacts: Describe the environmental impacts of your technology. How does the proposed technology avoid negative environmental impacts?15
Scalability: Describe how your technology could be implemented in the field. Can the proposed technology be deployed at industrial scales? Would the proposed technology be cost-effective at scale?15
Technical Maturity: Describe the technical readiness of your technology. How developed is the proposed technology? 5



Participation Eligibility:

The Prize is open to anyone age 18 or older participating as an individual or as a team. Individual competitors and teams may originate from any country, as long as United States federal sanctions do not prohibit participation (see: If you are a USDA-ARS employee, a Government contractor, or employed by a Government Contractor, your participation in this challenge may be restricted.

Submissions must be made in English. All challenge-related communication will be in English.

No specific qualifications or expertise is required. Prize organizers encourage outside individuals and non-expert teams to compete and propose new solutions.

To be eligible to compete, you must comply with all the terms of the challenge as defined in the Challenge-Specific Agreement.

Registration and Submissions:

Submissions must be made online (only), via upload to the website, on or before 5:00pm ET on December 15, 2020. All uploads must be in PDF format. No late submissions will be accepted.

Intellectual Property Rights:

As detailed in the Challenge-Specific Agreement – Innovator agrees that: (i) all Submissions become The United States Governments’ property and will not be returned; and (ii) Challenge Sponsor and its licensees, successors and assignees have the right to use any and all Submissions, and the names, likenesses, voices and images of all persons appearing in the Submission, for future advertising, promotion and publicity in any manner and in any medium now known or hereafter devised throughout the world in perpetuity.

Title in all intellectual property rights, if any, and all inventions, patents, patent applications, designs, copyrights, trademarks, trade secrets, software, source code, object code, processes, formulae, ideas, methods, know-how, techniques, devices, creative works, works of authorship, publications, and/or other intellectual property (“Intellectual Property”) developed by Innovator as part of the Submission will remain with Innovator, subject to the following conditions:

If Challenge Sponsor notifies Innovator that Submission is eligible for a Prize, Innovator will be considered qualified as a finalist (“Finalist”). To receive a Prize, Finalist must agree to grant The United States Government an irrevocable, royalty free, perpetual, sublicensable, transferable, and worldwide license to any Intellectual Property developed by the Innovator as part of or demonstrated by the Submission and to use and permit others to use all or any part of the Submission including, without limitation, the right to make, have made, sell, offer for sale, use, rent, lease, import, copy, prepare derivative works, publicly display, publicly perform, and distribute all or any part of such Submission, modifications, or combinations thereof and to sublicense (directly or indirectly through multiple tiers) or transfer any and all such rights. Notwithstanding granting The United States Government such license for any Intellectual Property demonstrated by the Submission, Finalist retains title (e.g., ownership) of such Intellectual Property.

Additional Information

  • By participating in the challenge, each competitor agrees to submit only their original idea. Any indication of "copying" amongst competitors is grounds for disqualification.
  • All applications will go through a process of due diligence; any application found to be misrepresentative, plagiarized, or sharing an idea that is not their own will be automatically disqualified.
  • All ineligible applicants will be automatically removed from the competition with no recourse or reimbursement.
  • No purchase or payment of any kind is necessary to enter or win the competition.
  • Void wherever restricted or prohibited by law.
Updates 12

Challenge Updates

Two Week Warning

Dec. 1, 2020, 9 a.m. PST by Natalie York

There are only TWO WEEKS left to submit your solution for the Protecting the Natural Flavor of Catfish Challenge. The early bird definitely gets the worm - so don't put it off! Be sure to have at least 75% of your submission complete a full week before the deadline for maximum flexibility. We'd hate to think you worked hard on a submission, just to miss the deadline by a hair (that's right - no late-night, sad email exceptions - the cut-off is real, folks!)

All that aside, thanks so much to all of you for your interest. Crowdsourcing is nothing without the crowd, and well, that's you. Yeah, you.  

We can't wait to see what the winning solution looks like.

Best of luck to all!

Cyanobacteria 101

Nov. 25, 2020, 11:30 a.m. PST by Despina Maliaka

Article by Hannah Weiss

Have you ever seen a greenish liquid floating on top of a body of water? At first glance, it may not seem like much.

The organism, known as cyanobacteria, is actually a key component of many ecological processes and a vital part of life on Earth. However, too much cyanobacteria can be a bad thing. Cyanobacteria can cause ecological harm by outcompeting other organisms,  release toxic compounds, and cause unpleasant tastes and flavors in fish.

To figure out how to mitigate some of these harmful impacts, we first have to learn about how cyanobacteria function.

A picture of blue-green algae on the surface of water
A picture of blue-green algae on the surface of waterImage by armennano from Pixabay


What are cyanobacteria?

Cyanobacteria are microscopic organisms that live in water. They are bluish green in color, hence the name “cyan”. Cyanobacteria are commonly referred to as blue-green algae. In reality, however, they’re a type of bacteria.

Unlike most bacteria, which are single-celled, some types of cyanobacteria are multicellular. This allows them to spread much faster than other types of bacteria. Blue-green algae is also photosynthetic, meaning that it consumes carbon dioxide and produces oxygen.

Blue-green algae plays many important ecological roles, both past and present. It was key to the formation of the Earth’s oxygen atmosphere about 2.4 billion years ago. It’s also important for plant growth because it is one of the only organisms that can convert nitrogen into a form that plants can use. 

However, cyanobacteria can also be harmful. When they build up on the surface of a body of water, the dense blooms prevent light from reaching below the water’s surface, making it difficult for anything else to grow. In addition, cyanobacteria can release toxic compounds that are harmful to humans and animals.


What is known about the compounds that cause off-flavors in catfish? 

Cyanobacteria naturally release taste and odor compounds into the water, which then impact the taste and smell of the fish living in that body of water these taste and odor compounds are non-toxic. However, they are highly unpleasant, and they pose major problems for the catfish industry. 

The main compounds that affect taste and smell are geosmin and 2-methylisoborneol (2-MIB). Cyanobacteria are the major contributors of these two compounds in aquatic ecosystems.

Geosmin is a neutral colorless oil that produces an earthy flavor. In fact, that’s where it got its name – the word “ge” comes from the Greek word for earth and “osme” means odor. In fish, geosmin can be detected at ranges from less than 1 to 10 micrograms per litre. Since farm-raised catfish have a relatively mild flavor, geosmin can be detected at low concentrations.

2-MIB, the other major taste and odor compound, imparts a musty flavor and odor. It is a water-soluble compound that is crystalline white solid at room temperature. In catfish, the average consumer can detect 2-MIB at 0.7 micrograms per litre.


How do these compounds affect the taste of catfish?

Unpleasant flavors mainly occur when the odor-causing compounds are absorbed across the catfish’s gill membranes. The compounds may also be absorbed in the stomach lining and intestines if the fish swallows contaminated water.

After entering the bloodstream, the compounds become concentrated in edible tissues – namely, fatty skin tissue and visceral fat. When a consumer bites into a catfish filet, the unpleasant flavors are noticeable.

A hand holding a young catfish in front of a green bucket full of other young catfish
A bucket of young catfishImage by Opeyemi Owolabi from Pixabay

Why do cyanobacteria affect catfish ponds in particular?

Cyanobacteria are most commonly found in shallow, slow moving, or still water.  They can multiply quickly in warm, nutrient rich environments, creating blooms that spread across the surface of the water.

Catfish require warm water, and they are raised in ponds — the perfect conditions for cyanobacteria to flourish. Cyanobacteria are especially prevalent in summertime catfish ponds, and they can bloom rapidly in these conditions.


What’s the solution?

Odor-causing compounds are one of many problems posed by blue-green algae, but it’s important to remember that the bacteria play an important role in many ecological processes.

The solution is not to eliminate blue-green algae altogether, but rather to control it and limit its spread. At the same time, scientists are trying to find ways to limit some of its unpleasant effects. 

For example, the United States Department of Agriculture – Agricultural Research Service is currently sponsoring a crowdsourcing challenge to find ways to eliminate unpleasant flavors in catfish contaminated by compounds found in blue-green algae. To find out how you can get involved, visit the HeroX challenge page.


Making a Splash: A Snapshot of the US Catfish Industry + Challenge Webinar Recording

Nov. 18, 2020, 11 a.m. PST by Despina Maliaka

Article by Hannah Weiss

Channel catfishImage by David Mark from Pixabay

Catfish is one of the most frequently consumed seafood products in the United States. Given that catfish is a good source of high-quality protein and has a great taste, it’s no surprise that pond-grown catfish comprise the largest sector of US finfish aquaculture.

The catfish industry is an important contributor to the US economy. In 2019, Catfish farmers in the US sold $379 million worth of catfish. Over the past decade, catfish farmers have produced an average of 347 million pounds of catfish per year.

The industry is especially important to the top three major producing states: Mississippi, Alabama, and Arkansas. The industry is also a major source of employment. 

Mango catfish tacosImage by platinumproperties1 from Pixabay

History of the Catfish Industry

The first commercial catfish ponds in the US began in the 1960s. In the 80s and 90s, production boomed, and the catfish industry became the largest of all US aquaculture industries.

However, the catfish industry declined steadily during the 2000s. The prices of feed increased due to the increased demand for biofuels, which increased production costs. At the same time, fish prices remained flat. The economic recession in 2008 further harmed the industry.

Although the catfish industry has not bounced back to its booming production numbers in the 80s and 90s, things are looking up. In the 2010s, market conditions started looking better for catfish farmers. Feed prices started to decline, and fish prices rose. Improved technologies also helped to intensify production and lower production costs.


Technological advancements are making a splash

Technological advancements have allowed for more intensive production and lower production costs, which has helped the industry to spring back in recent years.



Catfish farmers have found success by breeding channel catfish and blue catfish. Channel catfish grow quickly, spawn easily, and are tolerant of fluctuations in water quality and temperature.

Crossing channel catfish with the slower-growing, but larger, blue catfish has yielded promising results. Hybrid catfish generally grow faster, have better survival rates, and yield more meat than either the channel or blue catfish.


Intensification of production

Technological advancements have also allowed farmers to produce more catfish in smaller areas of water.

Split-cell ponds are one way to do this. In split-cell ponds, fish are housed in one small section of the pond and the rest of the water is used for oxygen production. The smaller fish ponds allow for more intense production.

As a result of these advancements, the productivity of catfish farms has increased considerably over the past decade. For example, Mississippi catfish farms’ productivity rose from 3,100 pounds per acre in 2011, to 5,700 pounds per acre in 2019.

Despite these successes, catfish farmers still face challenges that reduce productivity.


Issues that remain


One of the major challenges that catfish producers face are undesirable flavors that develop in response to blue-green algae exposure. The taste has been described as “earthy” or “muddy,” and it must be removed from the catfish before they can be harvested.

To remove the unpleasant flavors, farmers leave catfish in the ponds to allow the flavor-distorting chemicals to be flushed out. The harvesting delays lead to significant economic losses since the farmers are unable to sell the fish right away, the fish need to be fed for longer, and there is an increased risk of predation and disease.

Blue-Green AlgaeImage by armennano from Pixabay  

This is a common issue for catfish farmers. Instances of off-flavor cause production delays for approximately 50% of catfish ponds each year in the US, and off-flavored fish cost an estimated $15 to $23 million to catfish farmers in the US. 

Currently, the United States Department of Agriculture – Agricultural Research Service is turning to the public to help find ways to eliminate off-flavors in catfish. To find out more about ways to get involved, take a look at the crowdsourcing project.


COVID-19: an unexpected hurdle

The COVID-19 pandemic has put even more pressure on the industry. As restaurants have reduced operations in response to the ongoing public health crisis, the demand for seafood, including catfish, has fallen considerably. As a result, catfish producers have had to hold inventory for longer periods of time, and many have cut back or shut down operations.


What’s next?

Although the COVID-19 pandemic has cast things into uncertainty, the catfish industry as a whole is taking positive strides. Technological advancements have helped to increase productivity, and innovation continues to progress.

The industry has kept its head above water during challenging times in the past, and it isn’t going away any time soon.



We encountered some technical difficulties uploading the challenge webinar last week. Sorry for the inconvenience. Please see the recording below. 


Challenge Webinar Recording

Nov. 12, 2020, 1:30 p.m. PST by Natalie York

For all of those that could not attend the live Q&A webinar on November 10th, please see the recording below: 

A reminder to all participants to post outstanding questions in the forum at 

Casting a wide net: why the USDA is turning to crowdsourcing

Nov. 9, 2020, 6 p.m. PST by Despina Maliaka

Scientists in the United States Department of Agriculture’s Agricultural Research Service are turning to crowdsourcing to help figure out how to eliminate unpleasant flavors in catfish that have been raised in ponds contaminated with blue-green algae. The question has been plaguing scientists and farmers for decades — now it’s your turn to help solve it.


Who’s behind the challenge?

The group sponsoring this challenge is the USDA-ARS National Program for Aquaculture, a governmental organization that works to ensure the quality and safety of aquatic products. The USDA-ARS works with many different types of fish, and catfish are one of their main species of interest. ­­With this project, they are looking for ways to reduce or eliminate off-flavors in catfish raised in ponds. 


Why is this challenge important?

The USDA-ARS has identified off-flavors in catfish as a significant issue that affects the economy, the environment and the livelihood of farmers. 

When catfish are exposed to certain types of blue-green algae, they can develop unpleasant flavors. Current methods of improving the flavor take a long time, meaning that farmers deal with costly production delays. In fact, American farmers lose around $20 million each year due to off-flavors in catfish. “We need to help farmers consistently and efficiently produce an affordable, high-quality product that consumers enjoy, and want to eat again,” said Dr. Caird Rexroad, the head of the USDA-ARS National Program for Aquaculture.

“Helping catfish farmers avoid off-flavor will improve their production efficiency, increase profitability, and improve the well-being of fish through methods that have minimal environmental impacts,” he said.


Why turn to crowdsourcing?

For decades, scientists have been trying to figure out how to deal with this issue. They have made solid steps in the right direction, and they are now turning to crowdsourcing to explore new paths that have not yet been considered.

“Recently, ARS has begun looking to non-traditional innovation platforms to enhance our research programs and we expect to capture new ideas to solve this problem,” said Dr. Rexroad. “We are excited about the possibility of forming new partnerships that we would not have identified through traditional research processes.” The goal of this project is to develop new methods that are cost-effective and don’t result in harvest delays.

“Blue-green algae causes the problem but resolving the problem could take the form of controlling the algae, controlling the compounds the algae produce or preventing the algal compounds from being tasted by consumers,” said Dr. Rexroad.

In addition to helping solve a pressing issue, the winners of this challenge will also have the opportunity to work with ARS researchers to implement their solution.

“This challenge is about good ideas. We would like to partner with winning solvers to develop, demonstrate, and transfer technology to the catfish industry,” said Dr. Rexroad.


What’s next?

Looking beyond, a successful solution to this challenge could help eliminate off-flavors in other species of farmed fish like salmon and tilapia. “We hope that solutions developed for catfish may be more broadly applicable across species and production systems,” said Dr. Rexroad.


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