Fishbowl Adviser

Why Is My Pleco Hiding?

Plecos, also known as Plecostomus or “plecos,” are a type of fish that are commonly kept in aquariums. They are known for their unique appearance, with their armored plates and unique fins, and their ability to help keep tanks clean by eating algae. However, some plecos may exhibit behavior where they always hide and never come out. This behavior can be concerning for aquarium owners as it can indicate that the fish is not healthy or is experiencing stress.


There are several reasons why a pleco may hide and never come out, and understanding these reasons can help you encourage your pleco to come out and be more active in the tank.


Plecos are nocturnal fish that prefer low lighting levels. If the tank has bright lighting, the pleco may be hiding to avoid the light. To encourage your pleco to come out, you can try adjusting the lighting in the tank to a more subdued level, using a dimmer switch or placing a cover over the tank.

Tank Size

Plecos need a lot of space to swim and explore. They are known to grow quite large, up to 12 inches in length, so a small tank can feel cramped and stressful for them. To ensure your pleco has enough space, make sure the tank is at least 55 gallons for a single pleco.

Water Quality

Poor water quality can cause stress in plecos and lead to them hiding. It is essential to regularly check and maintain the water quality in the tank, including pH levels, temperature, and the levels of ammonia, nitrite, and nitrate. Plecos are sensitive to pH fluctuations and require a pH level between 6.5 and 7.5.


Plecos can be territorial and may hide if they feel threatened by other fish in the tank. To ensure your pleco feels safe and secure, make sure to choose tankmates that are of similar size and temperament, and avoid aggressive or territorial fish.


Plecos may hide if they are stressed due to changes in the tank such as new fish being added or a change in water conditions. To reduce stress, try to minimize changes in the tank, and give your pleco a hiding spot such as a cave or a piece of PVC pipe where it can retreat when it feels threatened.


Plecos will hide when they are full and not interested in food. Make sure to feed your pleco a balanced diet that includes both protein and vegetable matter, and try to vary the types of food you offer to keep your pleco interested. A good diet for plecos includes sinking pellets, algae wafers, and fresh vegetables like zucchini, cucumber, and lettuce.


Plecos can hide if they are ill or injured, and it is important to look for other signs of illness such as lethargy, lack of appetite, and cloudy eyes. If you suspect your pleco may be ill, it is important to consult a veterinarian or an experienced aquarium hobbyist for further advice.

pleco fish

How Can I Make My Plecostomus More Active?

If you’re looking to get your pleco to be more active, there are several things you can try. Here are some tips to help encourage your pleco to come out and be more active in the tank:

  • Provide plenty of hiding spots: Plecos like to have places to hide, so make sure to provide plenty of caves, PVC pipes, or other hiding spots in the tank. This will make them feel more secure and reduce stress.
  • Create a natural environment: Plecos are native to rivers and streams, so try to replicate this environment in the tank by adding plants, rocks, and driftwood. This will provide natural hiding spots and give them more places to explore.
  • Feed them at night: As plecos are nocturnal, they will be more active at night. Try feeding them during the evening when they are naturally more active.
  • Keep the water clean: A clean environment is essential for plecos to be active. Make sure to perform regular water changes and maintain the right water parameters such as pH, temperature, and ammonia, nitrite, and nitrate levels.
  • Avoid overstocking: Overstocking the tank can make plecos feel cramped and stressed, which can lead to hiding. Make sure to have enough space in the tank for each fish to swim freely.
  • Offer a variety of food: Plecos are opportunistic feeders and need a variety of food. Offer them a variety of food such as sinking pellets, algae wafers, fresh vegetables, and even live food like brine shrimp or worms to keep them interested and active.
  • Consider tankmates: Plecos are peaceful fish and can get along with other peaceful fish, but they can become stressed if their tankmates are aggressive or territorial. Make sure to choose tankmates that are of similar size and temperament and avoid aggressive or territorial fish.
  • Provide a consistent environment: Avoid making sudden changes to the tank, such as adding new fish or changing the water parameters, as this can stress your plecos and make them hide.

By understanding the reasons why your pleco may be hiding, you can take steps to encourage it to come out and be more active in the tank. Keep in mind that plecos are nocturnal fish so they may be more active at night. If you notice any sudden changes in behavior or suspect your pleco may be ill, it’s always best to consult with a veterinarian or aquarium expert for further advice.


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