Fish serve a remarkably wide range of purposes, from the obvious (feeding people) to the surprising (treating burn wounds and brewing beer). Roughly 80% of the global fish harvest goes to human consumption, but the remaining share fuels industries as varied as agriculture, pharmaceuticals, cosmetics, and biomedical research.
Food and Nutrition
The most familiar use of fish is as a protein source. A 3-ounce serving of most fish delivers 15 to 25 grams of protein along with essential nutrients like vitamin D, calcium, potassium, iron, iodine, and choline. What sets fish apart from other proteins is its omega-3 fatty acid content, which varies dramatically by species. Farmed Atlantic salmon tops the list at about 1.8 grams of omega-3s per 3-ounce serving, while tilapia and cod provide only a fraction of that.
Fatty fish like salmon, herring, sardines, and mackerel deliver the highest concentrations. A serving of Atlantic herring contains roughly 1.7 grams combined, and sardines provide about 1.2 grams. Leaner species like shrimp, tuna, and tilapia still contribute omega-3s, just in smaller amounts.
Heart Health and Pharmaceuticals
Fish consumption has a direct connection to cardiovascular health. A large clinical trial published in the New England Journal of Medicine found that omega-3 supplementation produced a 28% reduction in heart attacks across the general study population and a 40% reduction among people who didn’t eat much fish beforehand. Among participants with two or more heart disease risk factors, the reduction reached 44%. Notably, omega-3s did not reduce stroke risk in the same study.
These findings helped drive the development of prescription drugs derived from fish oil. The FDA approved a concentrated fish-oil medication for patients with established cardiovascular disease or those with diabetes plus additional risk factors. It’s prescribed specifically for people with elevated triglyceride levels (above 150 mg/dL) and was shown to reduce the risk of major cardiovascular events, including heart attack and stroke, by 25% in high-risk populations over a five-year period.
Animal Feed and Aquaculture
A substantial portion of the global fish catch never reaches a dinner plate. Around 21 million tonnes of fish per year are processed into fishmeal and fish oil, representing about 23% of global capture fisheries. This figure peaked at 35 million tonnes in 1989 and has since stabilized at a lower level.
The aquaculture industry consumes the vast majority: 87% of global fishmeal and 74% of fish oil go to fish farming operations, creating a cycle where wild-caught fish feed farmed fish. The remainder is split among pig feed (7%), pet food (4%), and poultry feed (1%).
Burn Treatment and Wound Healing
One of the more unexpected uses of fish involves Nile tilapia skin as a biological bandage for burn patients. Tilapia skin is rich in type I collagen, the same structural protein found in human skin. Its collagen fibers are thick, organized in parallel and crosswise patterns that give the skin high tensile strength and elasticity, making it effective wound coverage.
Clinical trials have shown that tilapia skin grafts accelerate wound healing, promote new skin growth, and retain moisture to create the kind of environment that reduces scarring. Patients treated with tilapia skin needed fewer dressing changes and less pain medication compared to conventional treatments like silver sulfadiazine cream. The skin also has natural antimicrobial properties, which help prevent infection during recovery.
Biomedical Research
Zebrafish are one of the most widely used animals in laboratory science. About 70% of human genes have a direct counterpart in the zebrafish genome, and 82% of known human disease genes have zebrafish equivalents. That genetic overlap makes them powerful stand-ins for studying conditions that affect people.
Their value goes beyond genetics. Zebrafish embryos are transparent, which lets researchers watch disease processes unfold in real time under a microscope. Scientists have even developed a strain called “casper” that stays transparent into adulthood, allowing direct visualization of cancer formation and progression. For heart research, the zebrafish heart sits on the underside of the body where it’s easy to observe, and young zebrafish don’t depend on blood circulation for oxygen (they absorb it through their skin), so researchers can study severe cardiac defects without the fish dying immediately.
Fertilizer and Soil Health
Fish emulsion is a staple of organic gardening. It’s made from processed fish byproducts and typically has a nutrient ratio (nitrogen-phosphorus-potassium) ranging from 2-4-0 to 5-1-1, depending on the brand. Gardeners reach for it primarily when plants show signs of nitrogen deficiency, like yellowing older leaves.
Beyond the core nutrients, fish fertilizer supplies calcium, magnesium, sulfur, and other trace minerals. It also feeds beneficial soil bacteria, which improves soil structure over time. This makes it popular not just for the immediate nutrient boost but for long-term soil health in organic growing systems.
Cosmetics and Skin Care
Marine collagen, extracted from fish skin and scales, has become a major ingredient in the supplement and cosmetics industry. Fish-derived collagen has high bioavailability, meaning the body absorbs and uses it efficiently. In a randomized, triple-blinded clinical trial, women aged 45 to 60 who took a fish collagen supplement for three months saw a 35% reduction in wrinkles compared to their baseline measurements. Cheek skin elasticity improved significantly after just six weeks.
Brewing and Winemaking
A lesser-known use of fish involves isinglass, a protein derived from fish swim bladders. Brewers and winemakers use isinglass as a fining agent, a substance that binds to yeast particles and fermentation byproducts, pulling them to the bottom of the barrel and leaving a clear, clean liquid above. Guinness was the most widely recognized beer to use isinglass in its production (though it has since moved away from it). The process means trace fish products can show up in drinks that seem entirely plant-based, which matters for strict vegans.
Mercury and Safety Considerations
Not all fish are equally safe to eat regularly. The FDA categorizes fish into tiers based on mercury content. Species to avoid entirely due to the highest mercury levels include king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish, and bigeye tuna.
The lowest-mercury options, labeled “Best Choice” by the FDA, include salmon, sardines, cod, catfish, tilapia, shrimp, pollock, herring, anchovies, trout, flounder, and canned light tuna (skipjack). These can be eaten two to three servings per week. The distinction matters most for pregnant women and young children, but anyone eating fish several times a week benefits from choosing lower-mercury species.