What Do Cod Eat?

Cod are bottom-dwelling predators that eat a protein-rich diet of smaller fish, crustaceans, and mollusks. An adult Atlantic cod will eat herring, capelin, sand eels, squid, crabs, and lobsters. They are opportunistic feeders, meaning they eat whatever is plentiful and fits in their mouth. A large cod can consume prey up to half its own body length.

What Does a Wild Cod’s Daily Diet Look Like?

Wild cod spend most of their time near the ocean floor, hunting for food. Juvenile cod start by eating tiny zooplankton and small shrimp-like creatures called krill. As they grow, their jaws get stronger and their stomachs expand.

Adult cod are active hunters. Research published in the Journal of Fish Biology tracked cod stomach contents and found that 60-80% of their diet is fish. The rest is crabs, shrimp, and worms. Cod do not chew their food. They swallow prey whole, head-first when possible, so the fins do not get stuck in their throat.

One surprising detail: cod have been known to eat small seabirds that dive too close to the surface. This is rare but confirms they grab anything edible that moves.

How Do Cod Hunt and Catch Their Food?

Cod are not speed swimmers. They use a different strategy. They cruise slowly near the bottom and rely on a sudden burst of speed to ambush prey. Their swim bladder lets them hover without effort, saving energy for the strike.

They have excellent vision for low-light conditions. The North Atlantic gets dark at depth, and cod have adapted eyes that work well in dim water. They also use their barbel — a whisker-like organ on their chin — to sense food on the seafloor. It works like a feeler, detecting movement and chemicals in the water.

Cod hunt mostly at dawn and dusk. This is when their prey is most active and visibility is low enough to give cod the advantage. During the day they rest in deeper water.

What Do Farmed Cod Eat Compared to Wild Cod?

Farmed cod eat a completely different diet than wild cod. Wild cod eat natural prey. Farmed cod eat pellets made from fishmeal, fish oil, plant proteins, and vitamins.

The fishmeal in these pellets comes from wild-caught forage fish like anchovies and sardines. This creates a sustainability question: it takes about 3-5 pounds of wild fish to produce 1 pound of farmed cod. Some farms are now using more plant-based ingredients like soy and corn gluten to reduce this ratio.

Farmed cod also get added nutrients. Astaxanthin is added to give their flesh a pinkish color, similar to what wild cod get naturally from eating shrimp. Vitamin E and C are added as preservatives in the feed.

One key difference: farmed cod have higher fat content than wild cod because their feed has more oil. This changes the texture and flavor. Wild cod is leaner and firmer. Farmed cod is softer and milder.

How Does a Cod’s Diet Change With Age and Season?

A cod’s diet shifts dramatically as it grows. A 2-inch juvenile eats copepods and small plankton. At 6-8 inches, it switches to small shrimp and amphipods. At 12 inches, it starts hunting small fish.

Seasonal changes are just as important. In spring, cod follow spawning capelin into shallow waters and feed heavily. In summer, they eat more squid and crabs. In winter, their metabolism slows and they eat less, sometimes going weeks without a meal.

Water temperature also affects feeding. Cod are cold-water fish. They feed most actively between 2°C and 10°C (36°F to 50°F). When water gets warmer than 12°C, they stop eating and move to deeper, colder areas.

Spawning cod often stop eating entirely. During the spawning season in late winter and early spring, both males and females conserve energy for reproduction. They lose body weight during this period and regain it afterward by feeding heavily.

What Common Misconceptions Exist About What Cod Eat?

The biggest myth is that cod are scavengers that eat garbage. This likely comes from old stories of cod eating ship scraps. In reality, cod are selective predators. They prefer live, moving prey. They will eat dead fish if starving, but it is not their first choice.

Another myth is that cod eat only small fish. Large Atlantic cod regularly eat fish up to 18 inches long. There are documented cases of cod eating fish nearly as long as themselves. They simply swallow them whole.

Some people believe cod eat only at night. That is not accurate. Cod feed during low-light periods at dawn and dusk, but they also feed during the day in deeper or murky water where light is already dim.

A third misconception is that cod eat the same thing everywhere. A cod off the coast of Norway eats mostly capelin and herring. A cod on the Grand Banks of Newfoundland eats more crab and shrimp. Diet varies by location based on what is available.

What Happens When a Cod’s Food Supply Changes?

Cod populations are sensitive to changes in their food web. When herring or capelin populations crash due to overfishing or warming waters, cod suffer. They lose their primary food source.

Studies from the Northwest Atlantic Fisheries Organization show that when capelin declined in the 1990s, cod switched to eating more shrimp and crab. But these prey have less energy density than fish. Cod grew slower and had fewer eggs. The entire population shrank.

Climate change is warming ocean waters. Cod are moving north to stay in their preferred temperature range. This shifts them into areas with different prey. Some cod now eat more Arctic species like polar cod and amphipods. Whether this new diet supports healthy growth is still being studied.

Overfishing of cod also affects their diet indirectly. When large cod are removed, smaller cod and other fish compete for the same prey. This can lead to food shortages for young cod trying to grow.

What Should You Know About Cod Diet and Human Consumption?

What cod eat directly affects the fish on your plate. Wild cod that eat a natural diet of fish and crustaceans have firmer, flakier flesh with a clean taste. Farmed cod that eat pellets have a softer texture and a milder, sometimes oilier flavor.

The diet also affects nutrition. Wild cod has slightly higher protein and lower fat than farmed cod. Both are excellent sources of selenium, vitamin B12, and omega-3 fatty acids. The difference is small enough that most people will not notice a nutritional change.

Mercury levels in cod are low to moderate. The FDA lists cod as a “best choice” fish for pregnant women and children, meaning it is safe to eat 2-3 servings per week. This is because cod are not long-lived predators near the top of the food chain, so mercury does not build up as much as in tuna or shark.

If you care about sustainability, look for cod with a Marine Stewardship Council (MSC) certification. This means the cod was caught using methods that do not harm the ocean ecosystem or deplete the food supply for other fish.