Wild vs. Farmed Fish

Farming raises young fish in pens or ponds with feed until shipment; wild fish grow in the sea or rivers and are caught. Main differences:

Japan’s Ministry of Agriculture (MAFF) publishes annual sales of veterinary antimicrobials (antibiotics and synthetic antibacterials) for cattle, pigs, chickens, fish and other animals. The 2024 total was about 745 tonnes of active substance. By animal:

Pigs account for the most, followed by marine farmed fish. Sales for marine farmed fish rose from about 147 t in 2023 to about 192 t in 2024. The main drugs were oxytetracycline, erythromycin, ampicillin and sulfamonomethoxine.

The government sets which drugs may be used on farmed fish, with doses, methods and withdrawal periods before shipment. Since 2018, farmers in Japan need a written instruction from a specialist (such as a fish disease control officer) to buy antimicrobials, as part of national measures against antimicrobial resistance.

*Sales are the amounts reported by manufacturers multiplied by estimated shares per animal, and may differ slightly from actual use.

Even for the same farmed salmon, antimicrobial use differs greatly by country.

In Norway, use in farmed fish is lower than in land animals (about 4.5 t in 2023). In Chile, most use is to treat a bacterial salmon disease (piscirickettsiosis), with 97.9% given during the marine grow-out phase. When choosing farmed salmon, the country of origin is one useful guide.

Imported foods are checked by government monitoring for veterinary drug residues above set limits. When violations are found, inspections of that product from that country are strengthened. Examples for farmed fish:

Japan’s food composition tables list both wild and farmed values for some fish (raw, per 100 g edible portion). In all four, farmed fish had more fat and more EPA and DHA, and also more energy.

EPA and DHA are components of fish fat, so fattier farmed fish contain more per 100 g. Per gram of fat the difference is smaller, and for olive flounder and red sea bream the wild fish have more.

*Per-gram-of-fat values are calculated from the food composition table figures.

The fat of farmed fish depends on its feed. A study of more than 3,000 Scottish farmed salmon found EPA + DHA fell from 2.75 g to 1.36 g per 100 g between 2006 and 2015 as fish oil in feed was replaced with plant oils, though levels were still higher than in most other fish.

*Composition also varies with season, location and size.

Tilapia is a largely farmed fish, with about 5.3 million tonnes produced worldwide (2022). Its skin and scales are also used as collagen raw materials.

A study of 20 ponds at 18 tilapia farms in southern China found quinolones even in feed from sealed bags, tetracyclines in feed from opened bags, and sulfonamides and quinolones in pond sediment. The authors concluded that antibiotic-free feed alone may not prevent overuse, and that measures such as veterinary prescriptions may be needed.

Collagen is made from pig and cattle skin and bone, and from fish skin and scales. Wild or farmed, by source:

Dr.JAPAN uses collagen from the skin of wild cod caught in the North Atlantic. Wild fish grow without the feed or antimicrobials used in farming.

*Processed foods such as collagen products are not required to state whether the fish was wild or farmed. Ask the manufacturer if you want to know.

Is farmed fish dangerous?
Which drugs can be used and how is set by government, and imports are inspected. This page does not judge safety; it lays out what is used, so you can choose.

Which is more nutritious?
In the four fish compared (ayu, olive flounder, red sea bream, lean bluefin tuna), farmed fish had more fat, and so more EPA and DHA per 100 g and more energy. Per gram of fat the difference is small, and wild olive flounder and red sea bream have more. Farmed fish composition depends on feed.

Does farmed salmon use a lot of antibiotics?
It depends greatly on the country: about 0.5 t for farmed fish in Norway (2023), about 351 t in Chile (2024).

How can I tell wild from farmed?
In Japan, fresh fish sold in stores must be labeled “farmed” if farmed. Processed products such as mixed sashimi platters or grilled eel have no such obligation.

Is wild fish free of any concern?
This page compares only feed, antimicrobials and fat. Wild fish vary in their own ways, for example by season and location.