What Does a Pregnant Pleco Look Like?

The plecostomus is an egg-layer; as such, it does not get "pregnant" in the strict, biolgoical sense. Nevertheless, many aquarists use the term to describe a fish who is "gravid," or ready to lay eggs. Gravid plecos are easy to identify by their behavior and appearance.

  1. Likelihood

    • The plecostomus is notoriously difficult to breed, and a pair will generally mate only under ideal conditions in specially set up tanks. Unless an expert fishkeeper is actively trying to breed a pair, it is unlikely that a pleco will become gravid.

    Physical Appearance

    • A female pleco is usually gravid for only a few minutes or hours before she lays her eggs. During this time, she will look bloated or fat. The underside of her abdomen will protrude significantly, and it may be discolored due to the strain on her skin.

    Behavior

    • As she prepares to lay her eggs, a pregnant pleco will usually hide in a cave or other dark area. The male guards the entrance and promptly enters the area to fertilize the eggs.

    Eggbound Plecos

    • Occasionally, a pleco may be "fat" with eggs for an unusually long period of time, such as several hours or days. In this case, she is said to be eggbound, or unable release her eggs. The condition is untreatable and usually fatal.

    Sex Differences

    • There is no accepted standard for identifying sexual differences in plecos. In most cases, a hobbyist is unable to identify a pleco's sex unless it breeds.

    Other Causes of Pregnant Appearance

    • A pleco with a swollen abdomen is not necessarily gravid or eggbound. He or she may simply be overfed or could have a deadly infection known as bloat.