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Feeds for Aquaculture

While all animals needs to eat and all farmed animals need to be fed, aquaculture represents the most efficient method by which to convert feed to edible protein.  Research through the NOAA-USDA Alternative Feeds Initiative has accelerated progress toward reducing fishmeal and fish oil use in aquaculture feeds while maintaining the important human health benefits of seafood consumption.The remarkable progress in developing alternatives has reduced reliance on wild fish caught for this purpose. 

This series of Frequently Asked Questions (FAQs) addresses commonly asked questions related to feeds used in marine aquaculture.  We discuss what farmed fish eat and examine issues such as fishmeal and fish oil use in aquaculture and research efforts underway to bring greater sustainability to feed production.  If you have a question or concern that is not addressed here, contact us.

1. What type of food do farmed fish eat?
2. Do all fish eat the same thing?
3. Why use fishmeal and fish oil in the diets of farmed fish?
4. Where does fishmeal and fish oil come from?
5. What are forage fish used for?
6. What are fishmeal and fish oil used for?
7. Does aquaculture consume more wild fish than is produced?
8. Doesn’t harvesting pelagic fish have a detrimental impact on the food chain and other animals that depend on them?
9. What is being done to develop alternative feed ingredients?
10. What are potential alternatives to feeding fish to fish?
11. Can some of the waste that results from processing fish be used as fish food?
12. What about arguments that farmed fish are contaminated with mercury and other heavy metals?
13. Are there growth hormones in U.S. farmed fish?
14. Are antibiotics fed to fish to improve growth (or for any reason other than disease)?
15. Are antibiotics used at all in U.S. aquaculture?
16. Are farmed salmon fed or injected with dyes?
17. How many pounds of other fish are required to produce one pound of salmon?
18. Why don’t we just eat fish from these pelagic fisheries (i.e. Further down the food chain)?
19. Doesn’t uneaten fish food accumulate on the ocean floor and pose an environmental risk?
20. Does NOAA fund research on alternative feeds?
21. What are some of the constraints to reducing aquaculture’s dependence on wild fisheries?
22. What are specific areas of research that will lead to decreased dependence on fishmeal and fish oil?

 
1.  What type of food do farmed fish eat?

Farmed fish and shrimp eat feed that is specially formulated to contain all the essential nutrients they need to keep them healthy and growing and maintain the human health benefits of seafood consumption.  The ingredients are formed into pellets, similar in many ways to dry dog food.

There are about 40 essential nutrients needed by all animals.  Categories of essential nutrient include vitamins, dietary minerals, essential fatty acids and essential amino acids.  These are provided by a number of feed ingredients including fish, plant, and processing waste meals and oils.
 

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2.  Do all farmed fish eat the same thing?

No.  Fish nutritional needs vary by species.  Herbivorous fish eat a feed mixture that may contain plant proteins (e.g., soy, corn), vegetable oils, minerals, and vitamins.  In the wild, carnivorous fish such as salmon eat other fish.  Therefore, feeds for farmed carnivorous fish (as well as many herbivorous fish) include fish oils and proteins as well as plant proteins, minerals, and vitamins that achieve the nutrition requirements of the fish and offer health benefits to humans.  Traditionally, diets for carnivorous fish contained 30-50% fish meal and oil; however, continued research is leading to greatly reduced reliance on these ingredients.

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3.  Why use fishmeal and fish oil in the diets of farmed fish?

While fish and shrimp don't need fishmeal and oil in their diets, these ingredients have almost a perfect balance of the 40 or so essential nutrients that animals need to be healthy and grow – the same reason that seafood is so good for humans as well.

Fishmeal is a natural and well-balanced source of high-quality protein.  As ingredients in aquaculture feed, fishmeal and fish oil supply essential amino acids and fatty acids reflected in the normal diet of fish.  Fish oil is a major natural source of the healthy omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).  These fatty acids are not made by the fish, but become concentrated in fish further up the food chain from the marine phytoplankton (microscopic marine algae and microbes) that do synthesize them.

Through research, we are learning that other combinations of ingredients can achieve the balance of the 40 essential nutrients.  Affordable replacement ingredients for fishmeal and fish oil are becoming increasingly common, which is leading to declining percentage on those ingredients in farmed fish diets.

Including ingredients like oils from phytoplankton maintain the nutrient requirements of the final product without depending on fish oil.  The economics of using blended oils is improving as fish oil prices rise and the technology to produce phytoplankton (and other replacement ingredients) improves.
 

 
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4.  Where does fishmeal and fish oil come from?

About ¾ of the fishmeal and oil are produced from the harvest of small, open-ocean (pelagic) fish such as anchovies, herring, menhaden, capelin, anchovy, pilchard, sardines, and mackerel.  These fish have short life cycles and are capable of rapid reproduction and stock replenishment.  The other ¼ is generated from the scraps produced when fish are processed for human consumption.

The United States is a small net producer of both fishmeal and fish oil.  The largest U.S. fishmeal and oil production comes from menhaden caught in the east coast and Gulf, the second largest component of US production comes from fish processing trimmings produced in Alaska’s seafood industry.
 

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5.  What are forage fish used for?

The small, open-ocean fish that are caught in industrial fisheries are consumed directly, used as bait in commercial and recreational fisheries and in lobster traps, used as ingredients in the feed for aquaculture, pigs, poulty, cattle, and pet food; and are converted into fish oil pills.

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6.  What are fishmeal and fish oil used for?

Fishmeal and fish oil supply several major industries because they are natural ingredients of high nutritional value.  While they have been major ingredients of swine and poultry feeds for many decades, a growing percentage of these resources have been used to manufacture aquatic feeds. This is due to the worldwide growth of aquaculture over the past two decades.  Demand for fish oil in the supplement industry also is rising rapidly.

Fishmeal and oil are beneficial components of the diets of farmed fish.  Because of this, aquaculture producers have been willing to pay more for these ingredients.  As well, substitutes to fishmeal and oil have long been developed for terrestrial animal agriculture, while substitutes for aquaculture are just now coming online.  With rising costs for fishmeal and oil, aquaculture producers are developing cost-effective, yet healthful alternatives. 
 

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7.  Does aquaculture consume more wild fish than is produced?

When aquaculture is considered as an aggregate industry, the answer is no.  Globally, aquaculture uses about half a metric ton of wild whole fish to produce one metric ton of farmed seafood, meaning that aquaculture is a net producer of protein.

Feed conversion ratios (the amount of feed eaten by a fish related to the amount that fish provides for human consumption) vary among species, but farmed fish are far more efficient at converting feed than wild fish or other farmed animals such as cows and pigs.

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8.  Doesn’t harvesting pelagic fish have a detrimental impact on the food chain and other animals that depend on them?

Forage fish serve a dual function of contributing to overall ecosystem biomass and supporting global food supply, the latter through both direct human consumption and providing feed for terrestrial farming and aquaculture.  There is concern that ecosystem function is reduced at current catch levels; addressing this concern happens through fishery management rules (such as catch quotas) within individual capture fisheries.  For a discussion of marine resources and sustainability, click here .

Aquaculture is one of many end-uses for harvested forage fish, which also include providing fishmeal in diets of livestock, serving as baitfish for commercial and recreational fisheries, and – increasingly – as nutritional supplement and pet food ingredients.  In the absence of aquaculture, these fish would be consumed by other industries.

The world supply of fish from pelagic fisheries has remained relatively constant over the past twenty years at around 6 million metric tons.  These types of fish generally are capable of rapid reproduction and stock replenishment.  Many pelagic fisheries are recognized as successfully regulated and many stocks are fished at levels below the biomass that achieves maximum sustainable yield.  Careful fisheries management, including quota and catch limit systems, maintains the sustainability of these fisheries over time.

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9.  What is being done to develop alternative feed ingredients?

Future growth of marine finfish and shrimp aquaculture will need protein and oil sources greater than current fishmeal and fish oil production can satisfy.  NOAA, in partnership with the U.S. Department of Agriculture (USDA), launched the NOAA-USDA Alternative Feeds Initiative in 2007 to accelerate the development of alternative feeds for aquaculture.  The purpose of the Alternative Feeds Initiative is to identify alternative dietary ingredients that will reduce the amount of fishmeal and fish oil contained in aquaculture feeds while maintaining the important human health benefits of farmed seafood.

In addition to looking for substitutes, research is examining how farmed fish utilize feed, varying formulations, timing dietary needs with developmental stages, and other strategies to improve feed use efficiency.

Ultimately, the initiative will lead to the commercialization of alternatives for some species that will result in reduced dependence on marine fish resources by feed manufacturers and seafood farmers worldwide.  The biggest challenges for researchers are to develop alternative ingredients that fish will eat, that supply the nutrition fish require to grow, and to make available alternative ingredients that are commercially viable.  Current research, including that being done through the NOAA-USDA Alternative Feeds Initiative, is making great strides toward overcoming these challenges.

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10.  What are potential alternatives to feeding fish to fish?

Potential alternative include meals and oils from plants (the greatest source of protein and edible oil on earth), fish processing waste, yeast, bugs and other special meals, and even seaweed.  Potential alternative ingredients already in use include soybeans, barley, rice, peas, canola, lupine, wheat gluten, corn gluten, other various plant proteins, yeast, insects and algae.  Other sources that show great promise include waste from bio-energy and bio-plastic production and fish processing waste (trimmings).  Farmed seaweed has significant growth potential as a source of food and fiber for both aquaculture feed and human consumption.  Researchers have been successful in identifying alternatives that grow fish and help maintain the human health benefits of eating seafood. 
 

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11.  Can some of the waste that results from processing fish be used as fish food?

Yes.  The use of fish processing waste (trimmings) for the production of fishmeal and oil may be used.  For example, discarded by-catch in 1994 was estimated to total 17.9-39.5 million metric tons (mt).  This is a potentially large source of fishmeal.  More recent estimates of by-catch of 20 million mt are equivalent to 25% of the reported annual harvest by marine capture fisheries.  In Alaska alone, the fish processing industry generates about 1.2 million mt of by-product waste annually, from which high quality fishmeal and oil suitable for aquatic feeds may be produced.
 

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12.  What about arguments that farmed fish are contaminated with mercury and other heavy metals?

No farmed fish are on the “avoid” list due to mercury.  These compounds enter and concentrate in organisms largely through what they eat. Just like feeds for other domestic animals, aquaculture feeds are regulated by the U.S. Food & Drug Administration (FDA) and Departments of Agriculture in respective states, with advisement from the Association of American Feed Control Officials (AAFCO).  The FDA and state agencies conduct inspections as well as collect and analyze feed and fish samples to help ensure that feeds and the fish that consume them meet strict state and federal requirements.  Formulated feed ingredients used in aquaculture are regularly monitored to avoid possible contamination of feed with methyl mercury.

According to the FDA and EPA, studies show that for people eating the standard U.S. diet, the health benefits of omega-3 fatty acids far outweigh the potential drawbacks of mercury toxicity due to fish consumption.  Specific advisories are in effect for pregnant women, those trying to get pregnant, nursing women, and children.  See our FAQ on Seafood and Human Health for more information.

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13.  Are there growth hormones in U.S. farmed fish?

Growth hormone is not used in U.S. aquaculture.  Although growth hormones may be given to other farm animals such as cattle and sheep, their use in food fish is prohibited by the U.S. Food and Drug Administration (FDA).  Even if it was allowed, there is no incentive to use it, as it has not been shown to improve growth or efficiency in farmed fish.  Certain additives such as pigments, antioxidants, and other nutritional supplements have been proven safe and their use in fish feeds is permitted by FDA regulation.

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14.  Are antibiotics fed to fish to improve growth (or for any reason other than disease)?

In the United States, antibiotics are not fed to fish for non-therapeutic reasons through their feed or any other mechanism.  The use of antibiotics for non-therapeutic purposes in aquaculture is prohibited by law.  Incidentally, antibiotics do not improve growth or efficiency in fish (like they do in cows, swine, and chickens).  However, antibiotics have been known to be added to fish food in other countries.

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15.  Are antibiotics used at all in U.S. aquaculture?

As vaccines have been developed for the major diseases that impact aquaculture (including salmon), antibiotic use has all but disappeared in the U.S.  There occasionally is still a need to use them in special cases approved by a vet.  All drugs, including antibiotics, used in aquatic species farmed in the U.S. have been proven safe and effective and are undetectable at the time of harvest (as prescribed by FDA withdrawal times).  At present, only three antibiotics are registered and sold for use in the United States as feed additives for disease control in farmed fish.  The use of parasiticides is similarly restricted by FDA regulations.

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16.  Are farmed salmon fed or injected with dyes?

No.  In the wild, salmon eat krill and other tiny shellfish that contain natural pigments called carotenoids, which are powerful antioxidants and precursors of vitamin A.   Carotenoids, specifically astaxanthin and canthaxanthin, give salmon flesh its distinctive pigment.  Farmed salmon are supplemented with natural and/or synthetic astaxanthin that is identical to the pigment that salmon get in the wild.  Both natural and synthetic astaxanthin are processed and absorbed by wild and farmed fish in exactly the same manner.

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17.  How many pounds of other fish are required to produce one pound of salmon?

None – there is no “requirement” for fish to be in diets for farmed salmon or any other fish.  It is possible to feed salmon on a fish-free diet.  However, inclusion of fish in the diets of farmed salmon reflects the diet of wild salmon and confers the nutrient benefits associated with eating salmon.  Until replacements (such as algae) with nutritional elements similar to fishmeal and fish oil are commercialized, salmon and marine fish will need some fishmeal and fish oil in their diet.  However, researchers are making significant progress in reducing the amount of fishmeal and fish oil used in the diets of farmed seafood while maintaining the human health benefits.

The answer to how much is used (as opposed to required) is a moving target, depending on how much fish meal and fish oil is used in any particular salmon diet.  Recent data indicates reflects that the production of one pound of farmed salmon uses the fish oil from about five pounds of wild fish (depending on the oil content of the species used), but the fishmeal from only 1.3 pounds of fish.  The excess fishmeal from those wild fish is used in the diets of other farmed animals.

Considered in the aggregate, aquaculture uses about half a metric ton of wild whole fish to produce one metric ton of farmed seafood.  The amount of fish you get “out” (as seafood) relative to the amount of fish you put “in” (in the diet) – known as “fish-in/fish-out” (FIFO) conversion ratios – vary greatly among species.  Piscivorous fish – especially those new to aquaculture – require more fishmeal and oil in their diet than omnivorous species.
 

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18.  Why don’t we just eat fish from these pelagic fisheries (i.e. further down the food chain)?

To a certain extent, we do.  Increasingly, species like mackerel, herring, sardines, and anchovies are sold for human consumption.  As well,  fish oil in the dietary supplement industry is the fastest growing segment of that market.  However, consumer demand for species such as salmon, grouper, cod, and tuna drives the market for both farmed and wild fish.  Pelagic fish (such as anchovy and menhaden) generally are in far less demand (especially in western countries) for direct human consumption.

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19.  Doesn’t uneaten fish food accumulate on the ocean floor and pose an environmental risk?

Jurisdictions that regulate net-pen aquaculture set limits to what can accumulate under aquaculture facilities.  In the U.S., this is typically set at “no net accumulation” on an annual basis.  Feed for farmed animals is the most expensive input to fish farming (about 60% of the cost of growing fish).  For this and environmental considerations, fish farmers take extreme precautions to avoid over-feeding.  Farmers use advanced technology including automated feeders and underwater cameras to provide feed and monitor consumption.  Due to these advances in technology and careful siting, feed accumulation on the ocean floor is much less of a consideration than it once was.  Additionally, fish farmers work with state regulators to monitor the benthic effects of their operations. 
 

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20.  Does NOAA fund research on alternative feeds?

The National Oceanic and Atmospheric Administration (NOAA), in partnership with the U.S. Department of Agriculture (USDA), launched the NOAA-USDA Alternative Feeds Initiative in 2007 to accelerate the development of alternative feeds for aquaculture.  The purpose of the Alternative Feeds Initiative is to identify alternative dietary ingredients that will reduce the amount of fishmeal and fish oil contained in aquaculture feeds while maintaining the important human health benefits of farmed seafood.

Since 1998, NOAA has been supporting alternative feeds research through the National Marine Aquaculture Initiative, a competitive grants program.  Through this program, the agency has funded nutrition projects for a variety of marine fish species including black sea bass, cobia, cod, flounder, shrimp, snapper, sablefish and tuna.  This research generated information on use of probiotics, identification of dietary requirements, and use of alternative proteins and processing byproducts.  Since the 1950s, NOAA Fisheries Service labs have worked on diet development for Atlantic and Pacific salmon, sablefish, black sea bass, lingcod, rockfish, and several other marine species.  NOAA labs helped develop methods for improved recovery and use of seafood processing waste and invasive species meals for use in aquaculture feeds.

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21.  What are some of the constraints to reducing aquaculture’s dependence on wild fisheries?

Fish meal and fish oil produced from wild harvest fisheries are among the highest quality proteins and lipids available.  For several decades, the supply has been stable but fully exploited; that is unlikely to change no matter if the demand is from aquaculture, agriculture, human consumption, or any other source.   Although NOAA, its partners, and others are making significant strides toward reducing and, in some cases, replacing fishmeal and fish oil in aquaculture diets, two major constraints exist.

• Growth in worldwide population and the related increase in demand for all types of food.  As landings from wild fisheries are limited to maintain healthy fish populations, the expanded supply of seafood will have to come from aquaculture fed on alternative feeds.  While this is a constraint, it also is an opportunity for the United States to develop environmentally-responsible commercial aquaculture and work with partners to improve aquaculture practices around the world.
  
• The technical challenge of alternative ingredients.  The challenges for researchers are to develop alternative ingredients that fish will eat and that supply the nutrition fish require to grow; and to make available alternative ingredients that are commercially viable.  Current research, including that being done through the NOAA-USDA Alternative Feeds Initiative, is making great strides toward overcoming these challenges.

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22.  What are specific areas of research that will lead to decreased dependence on fishmeal and fish oil?

The development of alternative feeds would benefit from increased investment in research and development in many areas.  Key among these is to develop cost-effective ways to produce the hearth healthy marine omega-3 fatty acids.  Continued evaluation of alternative protein and oil sources such as by-products from other industries (e.g., biofuel), fish processing waste, and newer sources such as worms, insects, and algae will yield insights into the nutrient profiles of alternative ingredients and how they may meet the nutrient requirements of farmed species.

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