Cows produce methane and chickens produce carbon dioxide….in fact, all animals do, so many people ask, do fish produce CO2?
Fish do produce CO2 during respiration, which means that the water taken into their mouths passes through the gills situated behind their heads.13
During this process, oxygen is absorbed from the water, while CO2 is released and the water is then eliminated.
This type of CO2 production is known as natural CO2 production, as opposed to man-made CO2 production.
But, what exactly is a fish carbon footprint? And, where does natural carbon dioxide come from?
This complete guide explains how much carbon dioxide a fish produces (along with the carbon footprint of X species of fish) and more.
How Can I Tell How Much CO2 Is in My Water?
Natural carbon dioxide (atmospheric) releases occur when the ocean out-gasses itself, volcanoes erupt, natural wildfires occur, large masses of vegetation is left to decompose, and animals such as cows belch.
An optical sensor is used to measure the level of infrared absorption, which measures the CO2 level in water.
Even though these natural CO2 releases have a detrimental effect on the atmosphere, there are natural carbon sinks on Earth to help offset the resulting CO2 emissions. These come in the form of photosynthesis, ocean absorption, and the existence of soil.
Natural carbon dioxide releases have occurred over millions of years, and during the past ice ages, the level of CO2 in the atmosphere has been kept at 300 ppm.
With the advent of human activity, the level of CO2 has risen close to over 416 parts per million, and is at the highest level it’s ever been.14
The below table indicates just how fast and constantly the level of CO2 has risen between 1999 and 2021.1
Year | The Concentration of CO2 in Water, Parts Per Million |
2021 | 416.45 ppm |
2020 | 414.24 ppm |
2019 | 411.66 ppm |
2018 | 408.72 ppm |
2017 | 406.76 ppm |
2016 | 404.41 ppm |
2015 | 401.01 ppm |
2014 | 398.87 ppm |
2013 | 396.74 ppm |
2012 | 394.06 ppm |
2011 | 391.85 ppm |
2010 | 390.1 ppm |
2009 | 387.64 ppm |
2008 | 385.83 ppm |
2007 | 384.02 ppm |
2006 | 382.09 ppm |
2005 | 379.98 ppm |
2004 | 377.7 ppm |
2003 | 375.98 ppm |
2002 | 373.45 ppm |
2001 | 371.32 ppm |
2000 | 369.71 ppm |
1999 | 368.54 ppm |
Read More About: 125 Facts About the Environment in 2022 You Might Not Believe
Do Fish Need Carbon Dioxide?
After answering the question, do fish produce CO2 the next logical question is, do fish need carbon dioxide?
CO2 plays an important role in the ultimate lifespan of fish. The balance should be just right because too little CO2 or too much CO2 could lead to fish dieoff.
So, do fish produce enough CO2 for plants?
Fish have the ability to produce enough CO2 for plants if said plants happen to be moderate light and grow underwater in an aquarium.15
Highlight plants or highlighted aquarium plants will most likely require extra CO2 to grow properly. Without adequate CO2, algae will start to bloom in an aquarium.
So then how much CO2 is needed in a planted aquarium?
A thriving aquarium requires sufficient light, enough nutrients, and adequate carbon dioxide. But the CO2 levels must also be monitored as too much carbon dioxide can kill the fish in the aquarium.
The typical CO2 level is between 15 and 25 parts per million. Anything over 30 ppm can be fatal for fish, therefore it is best to cap the CO2 at 25 ppm.2
Do you really need CO2 for aquarium plants?
Carbon Dioxide is the most vital element in most planted aquariums, but this does not mean that some aquarium plants cannot thrive without it.15
Setting up an aquarium tank without CO2 will require low-energy plants.3 But, fish add CO2 to the aquarium.
If it becomes clear that even the low-light and low-energy plants inside the aquarium require a CO2 boost, extra fish can be added.16 Fish can produce enough carbon dioxide to keep low energy plants healthy, while many fish can even keep medium-energy plants alive.
Do Fish Produce CO2? (Do Fish Produce Carbon Dioxide?)
The above information makes it clear that the answer to the question, do fish produce CO2, is yes they do.
But exactly how much do they produce after being caught?
How Much CO2 Do Fish Produce?
Once caught, how much CO2 do fish produce?
The below table indicates the GHG emissions released by different types of fish and seafood.4
Type of Fish / Seafood | CO2 Per Kg |
1. Farmed bivalves | 1.40 kg |
2. Wild bivalves | 11.40 kg |
3. Farmed carp | 6.95 kg |
4. Farmed catfish | 7.77 kg |
5. Cod/haddock | 5.13 kg |
Type of Fish / Seafood | CO2 Per Kg |
6. Wild flounder | 20.31 kg |
7. Wild herring/sardines | 3.88 kg |
8. Wild jack fish | 9.67 kg |
9. Wild lobster | 19.44 kg |
10. Farmed milkfish | 6.43 kg |
Type of Fish / Seafood | CO2 Per Kg |
11. Farmed freshwater fish | 18.91 kg |
12. Farmed marine fish | 11.60 kg |
13. Wild redfish/bass | 9.91 kg |
14. Farmed salmon | 5.10 kg |
15. Wild salmon | 6.88 kg |
Type of Fish / Seafood | CO2 Per Kg |
16. Farmed seaweed | 1.09 kg |
17. Farmed shrimp | 9.43 kg |
18. Wild shrimp | 11.96 kg |
19. Farmed bighead | 3.51 kg |
Type of Fish / Seafood | CO2 Per Kg |
20. Wild squid | 8.18 kg |
21. Farmed tilapia | 10.68 kg |
22. Farmed trout | 5.41 kg |
23. Wild tuna | 7.63 kg |
Read More About: How These Animals Live in Trees Is Changing How People Live in Houses
Do Fish Produce CO2? Fish Carbon Footprint
The fish carbon footprint is explained as follows:17
One serving of fish equal to 100g is the equivalent of 1.34 kilograms of CO2 emissions. This can be compared to driving 6.8 kilometers in a gasoline car and 0.73 m3 or CO2 gas emissions.
The below table indicates the percentage of production and emissions of the nine major aquaculture species including marine fish in China:5
Species | Production | % | Emissions % |
Marine Fish | 0.78 | 1.90 | 1.65 |
Marine Bivalves | 12.33 | 30.04 | 12.70 |
Marine Shrimp | 1.11 | 2.70 | 7.48 |
Freshwater Shrimp | 2.16 | 5.26 | 12.99 |
Other Fresh Water Fish | 3.01 | 7.34 | 10.84 |
Cyprinids | 19.51 | 47.53 | 46.82 |
Catfish | 0.40 | 0.97 | 1.10 |
Tilapia | 1.65 | 4.02 | 6.31 |
Fresh Water Bivalves | 0.10 | 0.24 | 0.11 |
Total | 41.05 | 100% | 100% |
Do Fish Produce CO2?
Following the question, do fish produce CO2, is the question, where do fish rank when it is compared to lobster, lamb, beef, and dairy?
A 2021 study found that wild fish, and other types of seafood, produced only a sixth of the emissions of beef, a fifth of the emissions of lamb or mutton, and half of the emissions of cheese.18
Also, in 2021 it was established that the production of meat-based food is responsible for around 60% of all food production emissions.
The below table indicates the estimated GHG emissions per 1 kg of food produced, including animal-based foods such as beef and lamb, as well as fish and plant-based foods:
Type of Food | GHG Emissions Per Kg of Food Produced |
Beef (herd) | 60 kg of carbon emissions per 1 kg of food |
Lamb & Mutton | 24 kg of carbon emissions per 1 kg of food |
Cheese | 21 kg of carbon emissions per 1 kg of food |
Beef (dairy) | 21 kg of carbon emissions per 1 kg of food |
Chocolate | 19 kg of carbon emissions per 1 kg of food |
Type of Food | GHG Emissions Per Kg of Food Produced |
Coffee | 17 kg of carbon emissions per 1 kg of food |
Farmed Prawns | 12 kg of carbon emissions per 1 kg of food |
Palm Oil | 8 kg of carbon emissions per 1 kg of food |
Pork | 7 kg of carbon emissions per 1 kg of food |
Poultry | 6 kg of carbon emissions per 1 kg of food |
Type of Food | GHG Emissions Per Kg of Food Produced |
Olive Oil | 6 kg of carbon emissions per 1 kg of food |
Farmed Fish | 5 kg of carbon emissions per 1 kg of food |
Eggs | 4.5 kg of carbon emissions per 1 kg of food |
Rice | 4 kg of carbon emissions per 1 kg of food |
Wild Fish | 3 kg of carbon emissions per 1 kg of food |
Type of Food | GHG Emissions Per Kg of Food Produced |
Milk | 3 kg of carbon emissions per 1 kg of food |
Cane Sugar | 3 kg of carbon emissions per 1 kg of food |
Groundnuts | 2.5 kg of carbon emissions per 1 kg of food |
Wheat and Rye | 1.4 kg of carbon emissions per 1 kg of food |
Tomatoes | 1.4 kg of carbon emissions per 1 kg of food |
Type of Food | GHG Emissions Per Kg of Food Produced |
Corn | 1.0 kg of carbon emissions per 1 kg of food |
Cassava | 1.0 kg of carbon emissions per 1 kg of food |
Soymilk | 0.9 kg of carbon emissions per 1 kg of food |
Peas | 0.9 kg of carbon emissions per 1 kg of food |
Bananas | 0.7 kg of carbon emissions per 1 kg of food |
Type of Food | GHG Emissions Per Kg of Food Produced |
Root Vegetables | 0.4 kg of carbon emissions per 1 kg of food |
Apples | 0.4 kg of carbon emissions per 1 kg of food |
Citrus Fruit | 0.3 kg of carbon emissions per 1 kg of food |
Nuts | 0.3 kg of carbon emissions per 1 kg of food |
The main takeaway from the above table is that while fish production produces far less CO2 emissions compared to meat such as beef and lamb, it is not as low on CO2 emissions as plant-based foods.6
How Does a Carbon Dioxide Unit Work?
A carbon dioxide unit or CO2 sensor works by monitoring infrared absorption at a wavelength of 4.3 μm. If infrared light is observed as being absorbed, it indicates the presence of CO2. Whenever infrared light is not absorbed, it indicates a lack of CO2.
Carbon dioxide levels can also be measured using photoacoustic spectroscopy and electrochemical CO2 sensors.
Furthermore, a carbon dioxide unit also refers to a unit of measurement – CO2 is typically measured in ppm (parts per million).
Carbon Footprint of Animals by Species
When looking at the carbon footprint of animals by species, the below table indicates the GHG emissions of livestock as estimated in MMT of CO2e.19,7
Livestock Animals | CO2 Emissions in MMT of CO2e |
Cattle | 5,024 MMT of CO2e |
Chickens | 829 MMT of CO2e |
Pigs | 819 MMT of CO2e |
Buffalo | 766 MMT of CO2e |
Small ruminants | 596 MMT of CO2e |
Other poultry | 82 MMT of CO2e |
Furthermore, global livestock is responsible for 7.1 gigatons of CO2 emissions every year, which constitutes 14.5% of anthropogenic greenhouse gas emissions.
- Cattle (herds of dairy and beef) are responsible for the highest amount of emissions, around 65% of the total livestock emissions (globally).20
- The production of feed from ruminants produces 45% of CO2 emissions, while enteric fermentation produces around 39% of CO2 emissions. The storage and production/processing of manure produce 10% of CO2 emissions.
- The use of fossil fuels for supply chain purposes accounts for around 20% of global livestock emissions, while milk from beef and cattle produces around 41% and 20% of emissions respectively.
- Following this is pork with 9% of CO2 emissions, buffalo meat/milk with 8% of CO2 emissions, and chicken/eggs with 8% of CO2 emissions.
- Small ruminant meat/milk adds 6% of CO2 emissions and the remainder of the emissions is made up of poultry and non-edible product emissions.
Emission intensity per product
- Beef – 300 kilograms of carbon dioxide equivalent per kilogram of protein.
- Ruminants (meat/milk) – 165 and 112 kilograms of carbon dioxide equivalent per kilogram.
- Dairy milk (cow), chicken, and pork are all below 100 kilograms of carbon dioxide equivalent per kilogram.8
Carbon Footprint of Meat
The carbon footprint of meat is indicated in the below table and compares the CO2 equivalents to other foods. This table also indicates the CO2 equivalents of miles traveled by car.9
Food Type | CO2 kg Equivalent | Car Miles Equivalent |
Lamb | 39.2 kg of CO2e | 91 |
Beef | 27.0 kg of CO2e | 63 |
Cheese | 13.5 kg of CO2e | 31 |
Pork | 12.1 kg of CO2e | 28 |
Food Type | CO2 kg Equivalent | Car Miles Equivalent |
Turkey | 10.9 kg of CO2e | 25 |
Chicken | 6.9 kg of CO2e | 16 |
Tuna | 6.1 kg of CO2e | 14 |
Eggs | 4.8 kg of CO2e | 11 |
Carbon Footprint of Chicken
The carbon footprint of chicken is explained as follows:
- 1.39 kg of CO2 emissions per 21 grams of protein
- This is equal to a square footprint of 17.48 square feet
- It is also equal to a water footprint of 17.80 gallons.
Overall, the environmental impact of chicken is almost 10 times lower than that of beef.21
- In total chicken produces 6.6 times less CO2 emissions.
- Chicken uses 16.6 times less land than beef.
- Chicken requires 4 times less water than beef.
This means that the cradle-to-grave CO2 chicken footprint is estimated to be 12.27 kilograms of CO2e per kilogram.10
Carbon Footprint of Vegan Diet
The carbon footprint of vegan diet has been touted for a long time as being the smallest out of all the types of diets which can help promote a globally green environment. It has been estimated that a meat-based diet produces at least 2 times the carbon ‘foodprint’ compared to a vegan diet.
The different diets are compared as follows (based on the average American diet):
- Meat-based diet- 3.3 tons of CO2 emissions per year
- Meat-less diet- 1.9 tons of CO2 emissions per year
- Vegetarian diet- 1.7 tons of CO2 emissions per year
- Vegan diet- 1.5 tons of CO2 emissions per year
The below chart indicates the carbon intensity of different foods including meat-based, and plant-based foods.11
Studies have also shown that wild seafood, including wild fish, has a lower CO2 footprint than beef (red meat), dairy (cheese), and chicken (poultry).
It has also been estimated that because marine fisheries provide food security for millions of people around the world, a concerted effort to restore global ocean’s could provide food for a billion people while lowering the CO2 footprint of food production.22
The below chart indicates the comparison of the CO2 footprint of wild fisheries and aquaculture compared to other types of foods:12
It is clear that aquaculture and wild fisheries are at the lower end of the carbon footprint scale.
It is also easy to see that the question, do fish produce CO2, has a far more complicated answer than just ‘yes’ when looking at the above information and statistics.
Frequently Asked Questions About Do Fish Produce CO2
Do Fish Produce CO2?
Fish produce CO2 as a by-product of breathing. The processing of fish and seafood products also emit CO2.
How Does Carbon Dioxide Affect the Fish?
While CO2 in water can help boost the health of fish, too-high levels of CO22 can cause fish to suffocate.
References
1Tiseo, I. (2022, June 21). Atmospheric CO2 concentrations worldwide 1959-2021. Statista. Retrieved December 27, 2022, from <https://www.statista.com/statistics/1091926/atmospheric-concentration-of-co2-historic/>
2Aquatic Warehouse. (2019, March 13). How Much CO2 Do You Need for a Planted Aquarium? Aquatic Warehouse. Retrieved December 27, 2022, from <https://blog.aquaticwarehouse.com/how-much-co2-for-planted-aquarium/>
3Gay, J. (2022). How to set up a planted aquarium without CO2. Swell UK. Retrieved December 27, 2022, from <https://www.swelluk.com/help-guides/how-to-set-up-a-planted-aquarium-without-co2/>
4Our World In Data. (2018, August 2). GHG Emissions Per KG Of Seafood. Our World In Data. Retrieved December 27, 2022, from <https://ourworldindata.org/grapher/ghg-emissions-seafood>
5Science Direct. (2022, August 1). Current status of greenhouse gas emissions from aquaculture in China. Science Direct. Retrieved December 27, 2022, from <https://www.sciencedirect.com/science/article/pii/S2772735122000555>
6Neufeld, D., Lu, M., & Di Grandi, T. (2020, February 10). Chart: The Carbon Footprint of the Food Supply Chain. Visual Capitalist. Retrieved December 27, 2022, from <https://www.visualcapitalist.com/visualising-the-greenhouse-gas-impact-of-each-food/>
7Tiseo, I. (2021, October 4). GHG emissions of livestock globally by species 2017. Statista. Retrieved December 27, 2022, from <https://www.statista.com/statistics/742355/emissions-of-livestock-animals-by-animal-worldwide/>
8Food and Agriculture Organization of the United Nations. (2022). FAO – News Article: Key facts and findings. Food and Agriculture Organization of the United Nations. Retrieved December 27, 2022, from <https://www.fao.org/news/story/en/item/197623/icode>
9Lappé, F. M. (2022). Carbon Footprint of Food. Green Eatz. Retrieved December 27, 2022, from <https://www.greeneatz.com/foods-carbon-footprint.html>
10Consumer Ecology. (2022). Chicken Carbon Footprint & Environmental Impact. Consumer Ecology. Retrieved December 27, 2022, from <https://consumerecology.com/chicken-carbon-footprint-environmental-impact/>
11Wilson, L. (2022, December 18). The Carbon Foodprint of 5 Diets Compared. Shrink That Footprint. Retrieved December 27, 2022, from <https://shrinkthatfootprint.com/food-carbon-footprint-diet/>
12Petsko, E. (2021, September 16). Wild seafood has a lower carbon footprint than red meat, cheese, and chicken, according to latest data. Oceana. Retrieved December 27, 2022, from <https://oceana.org/blog/wild-seafood-has-lower-carbon-footprint-red-meat-cheese-and-chicken-according-latest-data/>
13Iowa Department of Natural Resources. (2017, April 8). How do fish breathe? – DNR News Releases. Iowa Department of Natural Resources. Retrieved December 27, 2022, from <https://www.iowadnr.gov/About-DNR/DNR-News-Releases/ArticleID/1454/How-do-fish-breathe>
14Herring, D. (2020, October 29). Doesn’t carbon dioxide in the atmosphere come from natural sources? Climate.gov. Retrieved December 27, 2022, from <https://www.climate.gov/news-features/climate-qa/doesnt-carbon-dioxide-atmosphere-come-natural-sources>
15Florida Department of Agriculture & Consumer Services. (2022). Aquarium Water Quality: Carbon Dioxide / Aquarium Fish / Recreation and Leisure / Consumer Resources / Home. Florida Department of Agriculture & Consumer Services. Retrieved December 27, 2022, from <https://www.fdacs.gov/Consumer-Resources/Recreation-and-Leisure/Aquarium-Fish/Aquarium-Water-Quality-Carbon-Dioxide>
16NCBI. (2014, July 24). Effects of increased CO2 on fish gill and plasma proteome. PubMed. Retrieved December 27, 2022, from <https://pubmed.ncbi.nlm.nih.gov/25058324/>
17NCBI. (2022, January 25). Climate-Friendly Seafood: The Potential for Emissions Reduction and Carbon Capture in Marine Aquaculture. NCBI. Retrieved December 27, 2022, from <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8824708/>
18NCBI. (2020, May 29). Meat consumption: Which are the current global risks? A review of recent (2010–2020) evidences. NCBI. Retrieved December 27, 2022, from <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7256495/>
19British Columbia. (2022). Reducing agricultural greenhouse gases. British Columbia. Retrieved December 27, 2022, from <https://www2.gov.bc.ca/gov/content/industry/agriculture-seafood/agricultural-land-and-environment/climate-action/reducing-agricultural-ghgs>
20Quinton, A. (2019, June 27). Cows and climate change. UC Davis. Retrieved December 27, 2022, from <https://www.ucdavis.edu/food/news/making-cattle-more-sustainable>
21Business Wales. (2020, October 8). Part 1: Greenhouse gas emissions & environmental impacts of the poultry industry. Business Wales. Retrieved December 27, 2022, from <https://businesswales.gov.wales/farmingconnect/news-and-events/technical-articles/part-1-greenhouse-gas-emissions-environmental-impacts-poultry-industry>
22Buzby, J. (2022, January 24). Food Waste and its Links to Greenhouse Gases and Climate Change. USDA. Retrieved December 27, 2022, from <https://www.usda.gov/media/blog/2022/01/24/food-waste-and-its-links-greenhouse-gases-and-climate-change>
23Brian Yurasits. Unsplash. Retrieved from <https://unsplash.com/photos/brown-and-black-fish-on-wooden-surface-KhTywORJC74>
24Magda Ehlers. Pexels. Retrieved from <https://www.pexels.com/photo/peep-of-brown-chicken-1300375/>
25PublicDomainPictures, MartinStr, VMonte13, stevepb, Couleur, _Alicja_, ExplorerBob, ReinhardThrainer, RitaE, and JillWellington. Pixabay. Retrieved from <https://pixabay.com>
26Justin Miller. Flickr. Retrieved from, <https://flic.kr/p/2nDcveW>
27U.S. Fish and Wildlife Service. USGS. Retrieved from <https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=551>