What Do Damselfish Eat?

Damselfish are marine fish who generally inhabit coral reefs in tropical waters. They are also popular aquarium additions. Damselfish are highly territorial and aggressive, in part due to their unconventional farming practices. Damselfish in the wild have been known to fearlessly attack divers studying the reefs the damselfish inhabits.

  1. Farming and Cultivating

    • Damselfish will aggressively attack fish that come into their farm territory.

      It is not uncommon for fish to be grazers or nibblers of aquatic vegetation; damselfish take grazing to a new level, however, by farming and harvesting algae for food. The fish protect their "crop" of cultivated algae from other herbivorous and omnivorous species and even weed unpalatable algae from their territory. With careful pruning, the algae the damselfish farm grow at an exponential rate and are then harvested. Damselfish do not harvest their entire crops at once, but continue to cultivate them, eating only what they need.

    Algae

    • The preferred algae cultivated and farmed by damselfish is typically one of the species of Polysiphonia. The Polysiphonia genus covers a variety of red algae species, and is a filamentous algae that can grow up to a foot in length. Polysiphonia can be easily overwhelmed by other algae; the weeding the damselfish provides allows the algae to reproduce quickly and without interference. The relationship between the damselfish and Polysiphonia is known as mutualism, a co-existence that benefits both species.

    Plankton

    • Plankton is any creature that can only move vertically in water.

      Plankton is a common food source for many fish, including damselfish. A plankter cannot swim against currents and is borne through bodies of water by drifting. Although most recognized plankton include largely microscopic creatures, by definition some jellyfish are also considered a planktic species. Other examples of plankton include the fry of some fish, krill, shrimplike amphipods, floating bacteria, eel larvae and protists. Young damselfish eat plankton before farming algae and still continue to consume plankton as a food source if algae resources run low.

    Small Crustaceans

    • Damselfish themselves are prey of reef sharks and eels.

      In the wild, juvenile damselfish feed on small bottom-dwelling invertebrates, before moving on to algae. When you're selecting tank fish, choose damselfish species carefully, as some of the larger damselfish will kill and eat small crustaceans such as crab, shrimp and barnacles. The more aggressive aquarium damselfish, such as domino damsels and black-and-white damsels, are highly territorial. In addition to killing and eating tank crustaceans, they may also kill other fish; including other damsels. Choose reef-safe damselfish for your aquarium.