Food · emission factor
The Carbon Footprint of Fish
550 g CO₂e / 100g
Fish carries an average footprint of about 550 g CO₂e per 100 g — roughly a fifth of beef's 2,990 g and slightly below chicken's 620 g. That average hides a wide spread: small wild-caught pelagic fish like sardines can be among the lowest-carbon animal proteins, while trawled or air-freighted species climb far higher. Understanding what drives the number helps you choose seafood that fits a low-carbon diet.
Why fish has this footprint
Unlike cattle or sheep, fish produce no methane from digestion, and wild fisheries need no farmland or feed crops — which is why fish sits so far below ruminant meat. The main emission source for wild-caught fish is diesel burned by fishing vessels, and fuel use varies enormously by method: purse-seining schooling fish like anchovies or sardines is highly efficient, while bottom trawling for flatfish or dredging for shellfish can burn several times more fuel per kilo landed. For farmed fish, the picture shifts to feed production, which typically dominates the footprint, plus energy for pumps and aeration. Salmon farming lands near the overall fish average, whereas farmed shellfish like mussels — which need no feed at all — are among the lowest-carbon animal foods available.
How fish compares with other proteins
At 550 g CO₂e per 100 g, fish sits in the middle of the protein spectrum in the Poore & Nemecek (2018) dataset that underpins these figures. It is over five times lower than beef (2,990 g) and less than a quarter of lamb (2,420 g), comparable to chicken (620 g) and eggs (450 g), but still well above plant proteins: tofu comes in at 200 g and beans at just 100 g. In practical terms, swapping one weekly beef meal for fish saves far more carbon than agonising over which white fish to buy. Transport can change the maths, though — most seafood travels by sea or is frozen, but fresh fish flown in by air freight can multiply its footprint several-fold.
Wild-caught versus farmed
Neither is automatically better. Well-managed wild fisheries targeting abundant, schooling species have low fuel intensity and no feed footprint. Aquaculture — now supplying roughly half the fish people eat, per the FAO — avoids fishing fuel but adds feed, and some pond systems in warm climates can emit methane from sediments. Farmed bivalves (mussels, oysters, clams) are a standout: they filter-feed from the water, require no inputs, and can even improve local water quality. If you want a simple heuristic, small oily fish and farmed shellfish sit at the low end; trawled species, farmed shrimp, and anything air-freighted sit at the high end.
How fish compares
How to reduce this footprint
- ✓ Choose small pelagic fish like sardines, mackerel, and herring — they are fuel-efficient to catch and rich in omega-3s.
- ✓ Pick mussels, oysters, and clams often; feed-free farmed bivalves are among the lowest-carbon animal proteins.
- ✓ Prefer frozen or canned fish over fresh fish flown in by air, since air freight can multiply the footprint several times.
- ✓ Track your seafood meals for a few weeks to see how fish choices shift your food footprint compared with meat-based meals.
Frequently asked questions
Is fish better for the climate than chicken?
On average they are close: fish sits at about 550 g CO₂e per 100 g and chicken at 620 g. The spread within fish is much wider, though — sardines and mussels beat chicken comfortably, while trawled or air-freighted species can exceed it.
Why is fish so much lower-carbon than beef?
Fish produce no digestive methane and wild-caught fish need no farmland, feed crops, or deforestation — the factors that push beef to 2,990 g CO₂e per 100 g. The main cost for wild fish is vessel fuel, which is modest for efficient fisheries.
Is farmed fish worse than wild-caught?
Not necessarily — farmed salmon lands near the wild-fish average, and farmed mussels are among the lowest-carbon animal foods because they need no feed. The biggest variables are fishing method (trawling burns far more fuel), feed source for farms, and whether the fish travelled by air.
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Decarbonr turns meals and journeys into one clear daily CO₂e number — on your iPhone, on-device, private by design.
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Sources & methodology: see Research & scientific references. Figures are averages used by the Decarbonr app; real-world values vary by production system, country, and occupancy.