Fish food is plant or animal material intended for consumption by pet fish, such as goldfish, cichlids, catfish, etc. These food usually have nutrients in it to keep the fish alive.
Fish food can be prepared in many forms. Pelleted forms are often used for large fish and outdoor fish. Koi food often has additives in it to enhance their colour. Another popular form is flake food. Animal matter can be fed to fish through frozen or freeze dried cubes of bloodworms , daphnia and brine shrimp.
Commercial fish food is often designed to float and the fish then
feed at the surface. This allows better viewing of the fish in a pond.
Another type is Krill
Krill are shrimp -like marine invertebrate animals. These small crustacians are important organisms of the zooplankton, particularly as food for , seals, and a few seabird species that feed almost exclusively on them. Their scientific name is Euphausiids, after their taxonomic order Euphausiacea. The name Krill comes from the Norwegian word krill meaning "young fry of fish". whales
Krill occur in all oceans of the world. They are considered a keystone species near the bottom of the food chain because they feed on phutoplankton and to a lesser extent zooplankton , converting these into a form suitable for many larger animals for whom krill makes up the largest part of their diet. In the Southern Ocean, one species, the Antartic Krill, Euphausia superba, makes up a biomass of hundreds of millions of tonnes, similar to the entire human consumption of animal protein. Over half of thi biomass is eaten by whales, seals, penguins, squid and fish each year, and replaced by growth and reproduction. Most of the species display large daily vertical migrations making a significant amount of biomass available as food for predators near the surface at night and in deeper waters during the day.