What Is Krill That Is Fed to Fish?

Many tropical fish benefit from food with a little more punch than fish flakes; in their natural saltwater habitats, they feed on smaller fish or creatures such as krill. Krill often survive as part of ocean plankton, but you can find it available commercially to give your fish extra protein and vitamins.

  1. Krill

    • Small and similar in appearance to shrimp, krill eat phytoplankton and grow to about 2 inches in length. They often float within groups of zooplankton as an essential part of the oceanic food chain. Krill can gather in big swarms, sometimes large enough to be seen from space. Because these crustaceans are so numerous, often topping 6 billion tons of krill in Antarctic waters, many fish, such as cod, herring and halibut, as well as whales and seals eat them regularly.

    What Fish Like Krill

    • Krill is ideal for most aquarium fish who typically eat other fish. Although krill are native to a saltwater environment -- and thus are good on the menu for saltwater carnivores -- you also can use them as an alternative to feeder fish if you have freshwater predatory fish in your tank. Sea creatures who usually scavenge or stay near the bottom of the tank, such as starfish and crabs, benefit from the nutrition provided by sinking krill.

    How It Helps

    • Krill are packed with protein, which is essential to the diet of all fish predators. In addition, krill provide carbohydrates and antioxidants to fish. They supply fish with essential fatty acids, such as omega-3, and amino acids. Fish don't naturally produce amino acids such as lysine, relying on food sources such as krill to supply their needs. Krill also help tropical fish keep their brilliant colors by providing healthy carotenoids.

    Feeding Your Fish

    • Although some specialty aquarium supply stores offer expensive fresh krill, it's typically more cost effective to buy krill frozen or dried. Krill treated in those manners can be stored for longer periods, allowing you to use as much or little as necessary as the population of your tank changes. Dried krill comes loose or in blocks to help you measure the proper amount for your fish. Frozen krill is separated into small sections that you must thaw in aquarium water before feeding it to your fish. Only add as much krill as your fish will consume in about five minutes; any leftover krill can begin to decay and dirty up your tank.