Phytoplankton is green algae and a chief source of food for fish such as carp and catfish.
Plankton is any drifting organism -- plant, animal or bacteria -- found in water. This aquatic life form is a vital food source for marine life every aquatic environment, whether it be steams, rivers, lakes or oceans. Small and large fish rely on aquatic food source such as algae to support the food chain. Fish farmers collect plankton for the industrial aquaculture of trout, catfish and other food fish.
Types of Plankton
Phytoplankton is the collective term used to call different organisms that can include certain types of algae, bacteria, protozoa, crustaceans, molluscs and coelenterates, as well as some creatures belonging to different animal zooplankton phylum, such as rotifers, tintinnids, copepods and larvaceans. These are effectively the basis of life for marine and freshwater ecosystems by serving as the food for small as well as larger fish organisms.
Phytoplankton
Phytoplankton belongs to plant life that include diatoms, green algae and bacteria. It is possible for phytoplankton to flourish, provided they are under certain conditions. This in turn will lead to the increase of population of zooplankton, as these feed on phytoplankton. To make it easier to identify both kinds of plankton, think of phytoplankton as the plant-like organisms and the zooplankton as the animal-like creatures. Categorizing these as such is not without fault given that a lot of plankton does not have clear plant- or animal-like traits (these are in a third category, called protists). The criterion for dividing plankton into categories, include macroplankton, microplankton and nannoplankton, though again, there are no clear-cut delineations between these groups.
Zooplankton
As with phytoplankton, zooplankton serves as the main food source of small fish, which larger-sized fish eat, the food chain that starts from these microscopic creatures will be able to sustain underwater life. Zooplankton can be categorized into two different groups: temporary plankton are planktonic eggs and larvae belonging to benthos and nekton, while permanent plankton includes all of the creatures that spend their whole life cycle in a floating state.
Stocking Plankton in a Pond
Fish farmers that run commercial ponds stock plankton as they understand the importance of the organism to sustain the food chain amongst fish, especial for fry and young fingerlings. Maintaining a healthy food chain for fish requires a mixture of both phytoplankton and zooplankton along with bluegills, minnows, snails, freshwater clams and reptiles such as turtles as well as frogs, according to Zetts Fish Hatchery.
Fish that Feed on Plankton
Two examples of fish that feed on plankton are menhaden and silver carp. An adult menhaden goes through four gallons of water per minute in order to collect phytoplankton and zooplankton in their gills. Not only will this give the fish the opportunity to feed, it also allows them to cleanse the water, even in the context of an ocean environment. Menhaden (which has a large population), in turn, serve as the food for larger fish, such as tuna, striped bass, bluefish, halibut, mackerel, swordfish and cod.
Silver carp have a special filtration capacity that allows them to collect phytoplankton and zooplankton as small as pinheads through their gills. Their gill rakers are effectively sponge-like in nature and can absorb the microorganisms easily. Because of the mucus they secrete in their gills, the silver carp is able to capture the microscopic organisms. Unlike menhaden, silver carp are a threat to water habitats, as their neverending consumption of the phytoplankton and zooplankton can spell disaster for the habitat as it creates food shortage for the other fish living in the area.
Tags: phytoplankton zooplankton, food chain, food source, their gills, algae bacteria, allows them, collect phytoplankton