Are Plecos Nocturnal?

Plecos are nocturnal animals that are more active at night. They prefer to sleep or hide during day time and start their food-seeking journeys when the lights are out. 

In this article, you’ll understand the various characteristics of a nocturnal animal and how they apply to plecos. You’ll also learn more about plecos in general and how they differ from other types of fish.

Note: Plecos, also known as Plecostomus, are fish, but we’ll sometimes refer to them as animals throughout the article for ease of explanation.

Are Plecos Nocturnal?

As mentioned earlier, plecos are indeed nocturnal. But why are they more active at night? Many theories exist regarding the nocturnal nature of some animals.

Evolutionary biology seems to be the most accepted theory in the meantime. It’s said that some animals developed the instinct to escape diurnal animals by seeking food at night.

Albino Bristle Nose Pleco

Diurnal animals are those who are more active during the day. It’s said that nocturnal animals developed the night activity instinct to hide from their diurnal predators.

The theory believes that the animal who constantly hid at night managed to survive and pass on the night survival instinct to their offspring. With time, the entire population of the said animal became nocturnal.

Keep in mind that it’s not night-exclusive. You can still see nocturnal animals in the morning, but not as often as you’d see them at night. The same goes for diurnal animals.

What Makes Plecos Nocturnal?

Plecos are nocturnal because they have most of the nocturnal animal characters. Being active at night isn’t the only characteristic that makes an animal or a fish nocturnal.

Otherwise, most humans would’ve been nocturnal if you think about it.

So, besides being active at night, here are the other characteristics that made plecos nocturnal:

Large Eyes

Creatures with healthy eyes can involuntarily control the amount of light going inside them by controlling the size of their pupils. This process happens automatically as the muscles involved move without the control of the individual.

You may have noticed how some of the well-known night creatures, like owls have large eyes. This allows the pupil to even wider to collect more light at night.

Plecos, like owls, also have larger eyes than your average fish. This allows them to see better during low-light conditions and navigate their way at night.

Large Royal Panaque Pleco (panaque nigrolineatus)

Slow Swimming

Most species of nocturnal fish are slow swimmers. However, that’s not necessarily because of their inability to do so; it’s more of a vision problem.

While these nocturnal fish can see better at night, the situation reverses in the morning. This is because nocturnal animals generally have their eyes optimized for night vision. Conversely, diurnal animals’ eyes are optimized for daylight situations.

Well-Developed Lateral Line Organ (LLO)

Fish have what’s known as the lateral line organ/system or LLO. This system is basically a collection of sensory organs that they use to detect various stimuli around them.

Using LLO, plecos can feel the vibrations and movements around them. This is especially useful at night when predators are outside their field of vision.

The LLO can also detect pressure gradients around the pleco. This allows the fish to escape any dangerous currents that could overpower their slow swimming.

Solitary Personality

Animals and fish may lack the higher intelligence humans have, but that doesn’t stop them from having their own personalities.

Plecos often have a shy and solitary personality. They usually stay away from other fish and creatures in general, whether they are predators or not.

Plecos might get used to other creatures if they see them on a daily basis. However, that’s rarely seen in nature but common if you keep a couple of plecos in a tank.

A note to keep in mind is that there are over 150 different species of plecos, and almost all of them shouldn’t be kept in tanks.

Plecos may not be the most difficult fish to keep alive, but keeping them healthy is challenging.

  1. The Dark Colors

The most common colors that plecos come in are brown, black, olive green, or gray. These colors could be solid or have various patterns. However, the one thing that stays common is that the colors lean toward the darker spectrum.

This is another advantage that plecos have against predators. If you can hardly see prey that can both see better than you and even feel the vibrations around, then you’re less likely to nail that prey.

Are Plecos Predators?

People often associate the word nocturnal with eerie night creatures like owls and bats who feed on the flesh of other smaller animals.

Plecos, on the other hand, are very peaceful creatures. Some plecos, like the pleco catfish, can grow to a surprising 24-inch length, but they won’t go around chasing other fish like lions hunt deer, for example.

They would still eat them but not exclusively feed on them.

That’s because plecos, like humans, are omnivores, which means that they can survive on both plant and meat-based diets.

While they can eay anything, plecos often feed on:

  • Algae
  • Small crustaceans
  • Smaller fish
  • Worms
  • Larvae

Final Words

So, are plecos nocturnal? The short answer is yes. Plecos are nocturnal and will spend most of their awake time at night looking for food.

Their physical and mental characteristics make them prefer the nightlife over the daylight. This makes them less prone to predators and provides a better environment for them to hunt for their own food.

Keeping plecos in tanks is not recommended as they require larger tanks to accommodate their size. Additionally, maintaining their health stable is a thing that many people struggle with.