Properties of Janitor Fish

The suckermouth catfish, or Hypostomus plecostomus, is a type of fish native to South America that has been introduced to North America and Asia via the aquarium trade. The suckermouth catfish is also known as the janitor fish, due to its proclivity to attach itself to aquarium floors and glass and suck up dirt and algae. In this way, it helps aquarium maintenance, but it can be a pest if released into lakes or rivers.

  1. Physical Description

    • The janitor fish is dark in color and spotted along its body. It has armor-like rows of scutes along the upper portion of its body; the bottom portion has no scutes or armor. It can grow to 50 cm, though it averages 28 cm. It has a sucker-like mouth that gives it its name and which it uses for food consumption.

    Habitat

    • The janitor fish is a freshwater species native to Central and South America, especially Costa Rica, Guinea and Panama. However, it has been introduced to both North America and Asia via the aquarium trade, and their release -- intentional or not -- has resulted in their proliferation in lakes, ponds and rivers, especially in Singapore and Hong Kong. Janitor fish prefer tropical climates and drainage areas where algae is plentiful. Aquariums, which accumulate algae and dirt, are ideal habitats for these fish as well.

    Eating Habits

    • Janitor fish feed on algae and small crustaceans but also other dirt and waste products in their habitats or aquariums. They use their sucker-like mouth to latch onto areas and vacuum up their food. The janitor fish is nocturnal and typically feeds at night. However, aquarium life can alter this pattern and cause it to feed during the day as well.

    Janitor Fish in the Wild

    • In non-native areas where janitor fish have been released into the wild, they compete with other fish for food. They multiply at a fast rate and eat all available resources, to the detriment of other fish in their area. Janitor fish also have a natural resilience that allows them to survive on scarce resources and in difficult environmental conditions, especially because they have no natural predators. This has posed problems for fishermen and enthusiasts of fish varietal proliferation. However, fishermen are now looking into ways to make the janitor fish -- not typically considered an eatable fish -- useful to humans, including using its oil as biofuels.