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What Type of Fish Eat Phytoplankton?

Phytoplankton is plant life, providing food for many fish.
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In the waterways, the food chain consists of five foods: phytoplankton, zooplankton, tiny baitfish such as fathead minnows, panfish and shiners and game fish, such as largemouth bass, catfish and other large predator fish. The key to the food chain is phytoplankton, as it is the starting block for the food chain. Phytoplankton is essentially plant life made up of diatoms, green algae and bacteria. If the conditions are right, phytoplankton can flourish, and so will zooplankton, which feeds on phytoplankton. Small fish will eat zooplankton, the large fish will feed on the small fish, and the food chain will sustain life throughout the water.


A capelin is a tiny scavenger fish found in the Atlantic Ocean as well as parts of the Arctic. Capelins are part of the smelt family. This small fish feeds on thick populations of phytoplankton as well as zooplankton and tiny crustaceans. A capelin is an important fish within the food chain as it supplies nourishment for Atlantic cod. Additionally, seabirds, squid, mackerel, seals and even whales all prey on this small scavenger fish. Capelins, especially males, have a 90 percent mortality rate on spawning. They grow to about 1½ feet in length and weigh around 2 pounds.


Menhaden live in large schools within North Atlantic waters. This fish has significant concentrations in locations such as Nova Scotia, Canada and around central Florida. They gather in large schools that extend up to 40 miles. Menhaden is a member of the herring family. Its appearance is light silver. Menhaden average 15 inches and weigh as much as 2 pounds, according to the website Chesapeake Bay NOAA. Menhaden are filter feeders that live mainly on phytoplankton collected while swimming in the ocean. Menhaden strain phytoplankton from the water by their gill rakers, which form a specialized basket that essentially captures tiny plankton. Adult menhaden filter through 4 gallons of water a minute and collect various phytoplankton as well as zooplankton within their gills. Being a filter feeder not only allows menhaden to feed but also lets this fish cleanse (like a water purifier) the ocean environment. Because they are plentiful, menhaden are an important food source for a wide assortment of large fish, including tuna, bluefish, striped bass, cod, halibut, mackerel and swordfish.

Gizzard Shad

Gizzard shad fry are born with small teeth that allow them to catch zooplankton until reach the length of 1 inch. At this length, a gizzard shad loses its teeth and becomes primarily a filter feeder consuming phytoplankton as well as some tiny invertebrates. Part of the herring family, a gizzard shad is native to the freshwater and saltwater waterways of eastern North America. A gizzard shad can reach the length of 2½ feet and weigh approximately 4 pounds, according to the website Arkansas Stripers. Within a water ecosystem, gizzard shad play a key role in feeding on microscopic organisms and provide food for species such as striped bass and other large predator fish.

Silver Carp or Flying Carp

In the 1970s, silver carp made their way to North America from China as a means to control algae growth within agricultural fish farms. Due to flooding, the silver carp escaped from fish farms and spread throughout the Mississippi and the Missouri Rivers as well as many tributaries in the Midwest United States. Silver carp are also known as flying carp for their leaping ability that can send them 10 feet out of the water. A silver carp can grow up to 40 pounds and measure approximately 3 feet long. A silver carp is a filter feeder with a special filtration capacity that allows the fish to filter microscopic particles as small as a pinhead through its gill rakers. The gills rakers of the silver carp are like a sponge. With sticky mucus that secretes from the gills, the carp is able to capture phytoplankton. Silver carp are an invasive species and have an undesirable effect on water habitats. With the fish's specialized filtration capacity, it is able to consume much of the phytoplankton and zooplankton within a body of water, leaving a short supply of food for the rest of the fish.


Phytoplankton can cause massive fish kills and potentially biotoxins or harmful algae blooms that may affect many living organisms and coastal ecosystems. The effect on coastal as well as freshwater tributaries occurs when phytoplankton die and produce bacteria such as biotoxins or harmful algae blooms, which deplete oxygen throughout the water. Essentially, an outbreak of algae bloom causes suffocation of fish. Not only can phytoplankton have a negative effect on fish but they can also affect microscopic organisms such as zooplankton. In some cases, human beings who eat the fish within these fish kill zones can become ill.

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