Commercial fish food is built from a mix of protein sources, fats, plant-based fillers, vitamins, minerals, and preservatives. The exact recipe varies depending on whether it’s designed for carnivorous species like salmon, herbivorous fish like tilapia, or ornamental aquarium fish. But nearly all fish food shares the same core building blocks, combined in different ratios and processed into flakes, pellets, or wafers.
Protein: The Primary Ingredient
Protein typically makes up the largest share of any fish food formula. The traditional gold-standard source is fishmeal, a powder made by drying and grinding whole fish or fish trimmings. Fishmeal supplies the essential amino acids that mirror what fish eat naturally in the wild, making it highly digestible and nutritionally complete.
Because fishmeal is expensive and puts pressure on wild fish stocks, manufacturers increasingly blend in plant-based proteins. Soybean meal, pea protein concentrate, corn gluten, and canola meal all appear on ingredient lists. Vital wheat gluten is especially useful because it’s about 80% protein, higher than fishmeal or soybean meal, and its elastic, sticky texture helps hold pellets together during manufacturing. It essentially doubles as both a protein source and a natural binder.
Newer formulations are also incorporating insect meal, particularly from black soldier fly larvae. These larvae convert organic waste into high-quality protein and can replace a significant portion of fishmeal. In salmon feed trials, black soldier fly meal has successfully substituted about 35% of the fishmeal protein with promising results.
Fats and Oils
Fish need dietary fat for energy, cell function, and to absorb fat-soluble vitamins. Fish oil has traditionally been the main fat source in commercial feeds because it’s rich in omega-3 fatty acids (EPA and DHA). These fatty acids are critical for fish health, and fish can’t produce them on their own. They originate from marine phytoplankton and concentrate up through the food chain.
To reduce reliance on fish oil, many manufacturers now use plant-based oils from soybeans, canola, or flaxseed alongside oils extracted directly from algae or marine microbes. Algae-derived oils can supply the same omega-3s without harvesting wild fish. In aquarium foods, you’ll often see a blend of fish oil and vegetable oils listed among the first several ingredients.
Color Enhancers
If you’ve ever bought fish food marketed for tropical or ornamental species, it likely contains color-enhancing ingredients. Fish can’t produce their own red, orange, or yellow pigments. These colors come from carotenoids, compounds that must be supplied through food.
Astaxanthin is the most common color additive, used to boost red and orange pigmentation. It’s added at concentrations typically between 100 and 350 milligrams per kilogram of feed. Spirulina, a blue-green algae, is another popular addition that increases yellow and green tones on fish skin. Studies on discus fish found that increasing spirulina levels in feed produced noticeably brighter and more vivid coloring. For ornamental fish owners, the color of their fish is directly tied to what’s in the food.
Vitamins and Minerals
Every commercial fish food contains a vitamin and mineral premix to prevent nutritional deficiencies. The typical premix includes vitamins A, D, E, K, C, and a full suite of B vitamins (B1, B2, B6, B12, niacin, folic acid, biotin, and pantothenic acid). Choline, which supports liver function and fat metabolism, is added in relatively large amounts compared to other vitamins.
On the mineral side, formulas include iron, zinc, manganese, copper, iodine, selenium, and cobalt. These trace minerals support everything from oxygen transport in the blood to immune function and bone development. The exact amounts vary by species. Marine fish formulas, for instance, tend to include higher levels of vitamin E and inositol than freshwater blends.
Preservatives
Fish food is high in fat, and fat goes rancid. To prevent this, manufacturers add antioxidants that slow lipid oxidation and keep the food shelf-stable. The three most common synthetic preservatives are ethoxyquin, BHA (butylated hydroxyanisole), and BHT (butylated hydroxytoluene). Ethoxyquin in particular has been one of the most widely used antioxidants in fish and animal feeds for decades.
Natural alternatives like tocopherols (a form of vitamin E), vitamin C, and plant-derived flavonoids can also slow oxidation, but they tend to be less effective over long storage periods. Many premium or “natural” fish foods rely on tocopherols as their primary preservative and advertise the absence of synthetic options. The trade-off is a shorter shelf life.
How Flakes and Pellets Are Made
The physical form of fish food, whether it floats or sinks, how quickly it breaks apart, depends heavily on how it’s manufactured. The two main methods are pellet milling and extrusion, and they produce very different products.
Pellet mills use steam and moderate pressure (below 90°C) to compress ingredients into dense, heavy pellets. These pellets sink, which makes them suitable for bottom-feeding species. However, the relatively low heat doesn’t fully cook the starches and proteins inside, leaving them less digestible. Pelleted feeds also tend to crumble more easily, creating dust and waste at the bottom of the bag.
Extrusion, the method used for most flakes and floating pellets, pushes ingredients through a machine at high temperature and pressure. This fully cooks the starches, which then expand as the feed exits the machine, creating an airy, buoyant structure. Manufacturers can control exactly how much the feed floats by adjusting temperature, moisture, and machine speed. The cooking process also gelatinizes the starch so it acts like glue, giving extruded foods much better structural integrity in water.
The downside of extrusion is that the intense heat destroys certain vitamins. Vitamin C is almost completely lost during the process, and vitamins A and D are vulnerable to oxidation at high temperatures. To compensate, manufacturers spray vitamins onto the outside of extruded pellets after cooking or use heat-stable vitamin forms.
What Varies by Fish Species
Carnivorous fish like salmon and trout need diets heavy in animal protein and fish oil, often 40% protein or higher. Herbivorous species like tilapia and certain cichlids do well on formulas with more plant material, including spirulina, algae meal, and vegetable proteins. Omnivorous aquarium fish like goldfish or tetras get a balanced middle-ground formula.
The ingredient list on a bag of fish food reflects these needs. A high-end carnivore pellet might list whole fish meal, fish oil, and krill as its first three ingredients. A community tropical flake might lead with wheat flour, soybean meal, and fish meal in that order, with spirulina and astaxanthin further down the list for color. Reading the first five ingredients gives you a reliable snapshot of what you’re actually feeding your fish.