The Best Scavengers to Place in Aquariums

Updated July 20, 2017

Scavengers play a critical role in the health of fish in an aquarium. Scavengers will scrape algae off an aquarium's tiny gravel, plastic tank decorations, live plants and glass. When scavengers such as snails, freshwater clams, shrimp, koi or cory catfish are introduced into an aquarium, the water quality can improve. An aquarium also will require less cleaning when populated with scavengers.

Cory Catfish

A cory catfish is a small, speckled fish that grows no bigger than 3 inches. It spends most of its life at the bottom of a fish tank sucking up food remnants and algae that accumulate on the floor. The fish swims along and sweeps its head from side to side to pick up debris. This scavenger is a great choice for maintaining a small aquarium with gravel. It is docile and will not attack other fish within the aquarium.

Pond Snails

This creature's small, hard shell is a light or dark brown often with small black spots. The snail's body is brown or, in some cases, pinkish. Pond snails are a good addition to an aquarium because they will eat the green algae and phytoplankton growing on the tank's glass and decorations. The snails also eat decaying food or animal materials and fungal plant matter lying on an aquarium floor. However, one detriment is that pond snails reproduce rapidly and can overpopulate a tank.

Freshwater Clams

Freshwater clams are invertebrates that also are known as freshwater mussels. Sizes range from 1 inch to 2 inches across the shell. However, some varieties can grow up to 3 inches to 6 inches wide and live for five or more years, according to All About Aquarium Fish. Freshwater clams are popular scavengers because they are filter feeders, which means they feed by straining microscopic food particles found in an aquarium's water. Adding several freshwater clams to an aquarium is ideal for keeping the water quality fresh.

Ghost Shrimp

The ghost shrimp is an freshwater scavenger that will consume algae and leftover food. The ghost in its name comes from the transparent body that allows viewers the ability to see through the shrimp's exoskeleton. The ghost shrimp has a feverish appetite and moves about an aquarium constantly searching for food. This means that freshwater shrimp will keep the water clean by devouring algae. It also will reproduce if there is an amply supply of its species in an aquarium.

Koi (Japanese Algae Eaters)

Koi are colourful fish that originated in Japan. This ancestor of the carp is a bottom-dweller that feeds on algae accumulating on glass, plants and gravel. The koi's appearance makes this scavenger a bright addition to an aquarium. Koi are somewhat docile. However, as a koi matures it will develop aggressive tendencies about territory toward other fish. Owners should not place adult koi within a goldfish tank. It most often appears and function best in a yard pond. Remove it when it exhibits aggressive behaviour toward other fish.


Goldfish require little care as pets. However, goldfish can become sick because of parasites and diseases. A goldfish tank should be cleaned once every two weeks. Owners must remove fish droppings that accumulate at the bottom of the tank. Replace tainted water with fresh water. Ammonia levels from the waste can make it difficult for fish to breathe and encourage parasitic illnesses such as ich, white sores that will appear on the bottom of fish that leads to infection.

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About the Author

Thomas Ganio began writing in 2006 for the "Northern Virginia Daily," a community newspaper in Richmond, Va. As a freelance writer, he has also contributed to "The Maryland Springs Gazette" and the Parks and Recreation Department of Richmond County, Md. Ganio holds a Bachelor of Arts in social science and English from James Madison University.