Eric is an aquarium enthusiast with over two decades of experience caring for a wide array of tropical fish.
Plecostomus Care Guide
The common plecostomus is one of the most popular aquarium fish in the world. This is the “suckerfish” often seen stuck to the aquarium glass, munching on algae. Some fish keepers stock plecos hoping they will help control algae in their tank. Indeed, these fish do an excellent job of that, but they also come with a handful of concerns that are hard to ignore. Most novice fish keepers don’t realize that the tiny 3-inch fish they bought from the pet store is a monster in the making.
Scientific Name and Natural Habitat
The scientific name for the common plecostomus is Hypostomus plecostomus. It is classified within the genus Hypostomus and the family Loricariidae. However, there is a range of species in the aquarium trade often referred to as common pleco. In the wild, they populate the rivers and streams of northeastern South America as well as the islands of Trinidad and Tobago.
Note: For the purposes of this article I will not be differentiating between the species of "pleco". Unless otherwise noted, the information here applies to all.
Plecos can grow to an adult length of up to two feet. It is easy to see why this fish is not appropriate for all but the largest home aquariums. They are usually sold as small juveniles, only three or four inches in length.
There are smaller plecos you may consider. Rubbernose and bristlenose plecos only reach an adult size of about six inches. They are algae-eating fish like their bigger cousins, but much more appropriate for most tanks.
Plecostomus Care Sheet
Hypostomus Plecostomus / various
Minimum Tank Size:
Algae, sinking pellets, algae wafers, veggies
Peaceful community fish
Plecostomus Tank Size and Setup
An adult common pleco requires a 150-gallon tank, minimum. However, as juveniles, they can be kept in smaller aquariums as long as there is a plan in place to move them as they get bigger. Consider at least a 55-gallon tank to allow a young pleco room to grow.
Plecos are fairly hardly fish. Follow the general guidelines for tropical fish care and practice proper tank maintenance
- Water Temperature: 75-80 Degrees
- Ammonia: 0
- Nitrates:< 20 ppm
- Nitrites: 0
It should go without saying that a pleco should not be added to a new tank until it is fully cycled. It’s smart to test your water and keep an eye on your water parameters. I recommend the API Freshwater Master Test Kit. It’s affordable, and I have found it is accurate and easy to use.
Plants and Decorations
Plecos can be hard on live plants, as they attempt to scrub them of algae. For this reason, consider avoiding broad-leafed plants in your planted aquarium. Do make sure you have natural driftwood in the tank for your pleco to rasp on, as well as hiding spots where it can retreat when necessary.
Temperament and Behavior
Plecos are generally docile, but they can become more aggressive as they age. They can lash out at other fish at times. This can occur if their nutritional needs are not met and the behavior is especially prevalent at feeding time. As mentioned above, plecos can also demolish live plants as well.
As the plecostomus is a nocturnal fish, they are most active at night time. This means they need a few safe spots in the tank where they can hide during the day.
What do plecos eat?
Your plecostomus will eat algae in your tank, but that should only make up a part of its diet. You will need to feed both algae wafers and sinking pellets to make sure its nutritional needs are met. Also, consider adding some fresh veggies to its diet. Plecos are scavengers and will take advantage of leftover food that lands on the substrate.
As long as your plecos needs are met, you should have little trouble with this bottom dweller. Choose the correct tank size, keep it well fed, and make sure it is comfortable with plenty of hiding spots and you plecos could live for over a decade.
Best Plecostomus Tank Mates
Because plecos are hardy, peaceful fish, they are appropriate for a wide range of tank mates. Some of the fish from their same region of the world include:
Angelfish are large, new-word cichlids from South America. They grow up to a foot tall, and like the common pleco, they require a large tank. A pair of adult angelfish in a large planted tank looks amazing. They occupy the middle-to-top section of the water column. Freshwater angelfish care requirements aren’t difficult, but you do want to understand what you are getting into when you stock this popular fish.
Neons are another commonly available freshwater fish that hails from the same region as the plecostomus. Neons are schooling fish, which means they are going to be happiest in groups of six or more. This should be no trouble if you have a tank large enough to house an adult pleco. Other tetras you might consider are the rummy-nose, cardinal, and the larger black-skirt.
Cories are a type of bottom-dwelling catfish, like the pleco. But, unlike the pleco, they do not eat many algae. Instead, they serve as the clean-up crew for your freshwater tank, munching up old fish food, dead plant matter, and maybe even a few snail eggs. Remember that plecos require a little animal matter in their diets as well as algae and plant matter. If you stock cories, be aware that they will be competing with your pleco for some of the food. Make sure you feed enough sinking pellets for everyone!
These guys are among my favorite aquarium fish. They have an interesting shape, but an even more interesting behavior. When they are startled, they leap out of the water! This is a defense mechanism, and in the wild, the whole school may leap out of the water when a predator comes around. This means you want to make sure your tank is fully covered, and you want to avoid fast-moving fish that may scare them. They are schooling fish, so you want to stock six or more.
If you are going to have a pleco in a huge tank, you may as well have other large freshwater fish to take advantage of that tank as well. Silver dollars grow to about six inches across and should be kept in schools of six or more. A long tank is preferred, as these fish are quite active. Like the plecostomus, they are also tough on live plants and may eat their leaves.
Here are the answers to some frequently asked questions about the plecostomus:
How many plecos can I have in my tank?
You should only keep one plecostomus per tank. This is because they can be territorial, especially as they age, and having more than one can lead to aggression. By keeping only one pleco, you are also ensuring that there is enough food to go around.
Do plecos attack and eat other fish?
Plecos are generally docile, but they will eat dead and dying fish if they can. They do not usually attack live fish. If you do notice your pleco lashing out at other fish, it is likely because something is lacking in its diet.
How many years do plecos live?
The common pleco can live for ten years or more. You can increase the chances of your plecostomus living a long life by keeping him in a big enough tank, following smart tank management practice, and making sure he gets enough good food to eat.
Will plecos really clean your tank?
Plecos can clean up some of the algae in your tank. However, no fish or group of fishes can completely keep your tank clean. Most tank maintenance, including dealing with algae, is up to the human in charge of the aquarium.
What fish can live with plecos?
Plecos are peaceful, community fish that can live with most other tropical fish. You may wish to stock them with other large fish from the Amazon River region, where plecos are found in the wild.
Do plecos need a heater?
Yes! All tropical fish require a heater. Plecos are not cold-water fish. Even if they were, it would be a good idea to include a heater in the tank to make sure the water temperature never drops too far.
Should You Get a Plecostomus for Your Tank?
Most issues with the common pleco are remedied by keeping them in a large enough tank and making sure they get enough of the right food to eat. Otherwise, this is a very easy fish to keep.
Unfortunately, they are among the most misunderstood fish in the aquarium trade. I got my first fish tank almost four decades ago when I was a kid. It was a ten-gallon tank, and my parents took the advice of the pet shop owner and bought a common pleco to eat the algae. My parents didn’t know any better, and I certainly didn’t, but I expect the pet shop guy should have. I cringe when I think of that today.
These days, it is super easy to find out everything you need to know about a fish with a few minutes of online research. Yet, somehow, baby plecos continue to end up in 10-gallon tanks.
I’m not going to try to dissuade you from keeping this wonderful fish. Just know what you are getting into and plan accordingly. The common plecostomus is a very cool fish and, in the right setting, a wonderful addition to a freshwater tropical aquarium.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.