How to Tell if Your Pleco Is Happy? Common Signs

Plecos are great bottom feeders and an excellent addition to a community tank. But the problem with adding plecos to the tank is that you will hardly notice them moving around and acting normally during the day.

Many aquarists report that even at night, it is difficult to tell what their plecos are up to and whether they are happy. Have you been finding it difficult to tell if your pleco is happy?

Here are some common signs to tell if your pleco is happy. Read on to find out!

Common Signs of Happiness in Pleco

It is important to understand a fundamental truth about fish and emotions. Generally, fish do not have the mental capacity to feel such emotions as happiness, sadness, etc. They instinctively respond to the stimuli in their immediate environment.

This may include changes in water conditions, food scarcity, illnesses, and even the presence of another male in a territory claimed by one male.

Studies reveal that some species, like dolphins, have complex brains. They are capable of feeling a wide range of emotions. But plecos and several other fish species in the hobby do not have a complex brain capable of experiencing emotions.

Perhaps the appropriate word to use is “healthy” instead of saying “happy.” Things that contribute to your pet’s good health may include the appropriate water parameters, suitable lighting, and an excellent choice of compatible tank mates.

So what are the signs that you can look out for to be sure that your pleco is healthy?

Below are some of the signs to pay attention to:

Activity Under Dim Lights

One of the best ways you can tell that your pleco is happy is by watching how active it becomes in the dark. Plecos are slightly nocturnal. You may notice that you hardly catch them swimming freely and eating during the day.

This is because they will usually be under tank decorations during the day.

Naturally, they come from a dark environment. Plecos are native to the tropical water of South America. In the wild, these bottom dwellers are usually at the base of the water bodies they occupy. They spend time in these dimly lit parts of the water to search for food and to hide from predators during the day.

They are most active at night, so it should not come as a surprise when you see them hiding during the day and only coming out at night.

You want to provide a lot of covers and hiding places during the day. This will provide comfort and escape from the light, an essential need for plecos to be happy in your tank.

If your lighting system uses very powerful lights, it would be best to reduce the brilliance and dim the lights a little. Running a community tank may present some challenges, as other tank mates may require more light. You want to take care to keep only tank mates that will not be affected by the dim lights.

Sometimes, they may change from being solitary to being sociable in a community tank. This has been observed in the hobby. If your pleco is not active at night, you may want to investigate the reason to be sure that it is not suffering from any ailment. Happy plecos always come out to eat and have fun at night.

Feeling Safe Enough to Swim Around

Although plecos are often reported as solitary animals, experience shows otherwise. Contrary to popular belief, they are not so solitary, especially when living in a big community tank.

In instances like these, keeping as much as 2-5, depending on the species and size, can boost their confidence and make them feel safe enough to swim around the tank happily.

You can also use dither fish to make them feel safer enough to swim freely in the tank. Some small species that will do the trick include minnows and tetras.

If your fish is not swimming freely, this could be a sign that something is wrong. You may have to check the water parameters and other factors that usually cause health issues for fish.

If you keep a large aquarium, you want to also pay attention to the other inhabitants in the tank. Larger and more aggressive tank mates may be the reason your pleco is not feeling safe enough to swim freely.

Hangs on Tank Decorations

Plecos hanging around their favorite decoration pieces is one sign of happiness, especially during lights out. It is a common experience for pleco keepers in the hobby.

When a pleco begins to feel pretty comfortable in your tank, you will often find it hovering and sometimes hanging for long periods on its favorite piece of decoration in the tank. This piece of decoration could be driftwood, a cave, or a plant in the aquarium.

At other times, you may find them hanging off the glass. This is pretty normal behavior. You can be sure that your pet is happy with its environment when it exhibits these signs.


A “happy” or healthy pleco is an eating pleco. Appetite is perhaps one of the main signs of happiness and good health in plecos and many other fish species.

Plecos are largely herbivores but will also eat meaty food items if offered some. However, plecos mostly browse the aquarium for edible plant matter in the aquarium to consume. Many aquarists often feed their plecos some algae wafers.

The tactic is to leave the algae wafer in the aquarium for a few minutes before putting off the lights. The wafer should be finished before the next morning. Plecos usually eat well and will hardly stop eating unless they are full.

So, if your pleco is losing appetite, that loss of appetite is one sure way to tell that your pet is neither happy nor healthy.

It would be best to vary its diet first and ensure that you try out other feeding periods to be sure that the food offered is not the problem. You can offer some meaty foods, some cut vegetables, and some flakes to your pet to see how it responds.

You can also try live foods like worms and shrimp, as this will elicit a natural response from your animal.

If your fish rejects all these food options, there is a great chance that your pet needs more than the usual attention. You want to watch out for other signs like fatigue and abnormalities in body features such as skin color.

These could be a symptom of an illness or stress.

It would be best to examine your fish closely, check your care routine, the frequency of your water changes, and your water parameters.

Great Physical Condition

This is perhaps the most visible sign of good health and happiness in a pleco. There are several pleco species in the wild, but the species kept in the aquarium trade are relatively few.

If you are keeping plecos, understanding how they look when they are healthy is a great way to tell when they are not healthy or “happy.”

Generally, plecos are a special tropical freshwater Loricariidae family. This family of fish is commonly known as the Armored Catfish Family, and some of their features include a flattened body, long rows of protective scutes that cover the upper region of their head, and some parts of their bodies, etc.

One of the defining features of plecos, especially the species in the aquarium trade, is their color. They are usually dark-colored with white spots on their bodies. Other species may appear to have a lighter shade of gray and undefined white marks instead white spots.

You can tell if your pleco is not healthy and “happy” if you notice any concerning changes in its physical appearance. Although they often change their colors to evade predators in the wild, they will only lose the vibrance of their color in the aquarium when under stress or sickness.

You may notice their color fade when they sleep, but the vibrance usually returns when they wake up. However, you may notice their physical appearance deteriorate if they are under stress, sick, or dealing with other challenges like poor water quality, food scarcity, and aggressive tank mates.

You may see their color fade or their skin rot. When this happens, you can be sure that your pleco is neither happy nor healthy. It would be best to find the problem and fix it as soon as possible to improve your pet’s health and keep them happy.

Bottom Line

Remember that fish generally cannot feel such emotions as happiness or sadness. If your fish suddenly changes its behavior after the loss of a cherished tank mate, this is merely a response to the disappearance of the tank mate.

Schooling fish, in these instances, will lose confidence in swimming around. Over time, they will become confined to hiding places as their numbers dwindle.

The same applies when you feed your pet. The food spurs a response in them, but the rush does not literally translate to the feeling of excitement as humans feel it. So “happy” in this article is restricted to mean healthy.

But take note that some fish species have more complex brains that can appreciate a limited range of emotions.