Aquarium Fish

Plecostomus - Pleco Fish

The Common Pleco or Plecostomus can be a nice fish for the appropriate tank. It is usually referred to as Pleco because of the superstition that if you spell it fully or correctly your fish will soon die. So silly.

The common plecostomus is well known as an algae eater and can often be found stuck to the side of your aquarium. Many will get very large with the common variety getting to be almost 18 inches (46 cm) and will outgrow most aquariums! Don't believe it? Check out some of the member photos on the forum in the Plecostomus Photos thread.

As your pleco gets older they may eat algae less often and you will need to supplement their diet with algae wafers that sink to the bottom of your tank. Shrimp pellets that drop to the bottom of the tank are another favorite. Drop in the algae wafers or shrimp pellets after you turn off the lights for the day to prevent the other fish in the tank from getting the food before your pleco can get to it.

There are varieties that don't get as large, such as the Bristlenose Plecostomus which reaches about 5 inches in size as adults. Don't make the novice mistake of putting a common pleco in a small aquarium. Look into the smaller pleco species as mentioned. These common plecos need to be in ponds or very large aquariums.

Common Pleco Plecostomus

Pleco Food Ideas Video

Plecostomus, Pleco Care Facts

Scientific Name : Hypostomus plecostomus

Common Names : Suckerfish, Suckermouth Catfish

Care Level : Easy to moderate

Size : Up to 18 inches (46 cm)

pH : 6.5 - 7.5

Temperature : 73°F - 82°F (23°C - 28°C)

Water Hardness : 5° to 19° dH,

Lifespan : 10 - 15 years

Origin / Habitat : South America

Temperament / Behavior : Generally peaceful, but plecos can be aggressive toward others of the same species.

Pleco Breeding : It can be very difficult to breed them in a home aquarium.

Aquarium Size : Recommended to keep them in aquariums that are in the hundreds of gallons. Due to their potential adult size this is one of those species better left in the wild or kept in ponds. For the aquarium there are other smaller pleco species that are available. Smaller species include the Bristlenose pleco, the Gold Nugget pleco, Zebra pleco and the Clown pleco (linked in similar species below).

Pleco Tank Mates : Many, given the mostly peaceful nature of this fish.

Pleco Fish Disease : Freshwater Fish Disease - Diagnose, Symptoms and Treatment

Pleco Diet / Foods : Herbivore, try to supplement their diet with algae wafers

Tank Region : Bottom and the sides of the glass.

Gender : There are no visible differences between the male and female.

Author : Mike FishLore

Fish Forum : Pleco Forum

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Pleco Eating

Pleco Tips

From: Gene C.
These fish will grow to the size of the tank and if bought young are suitable for tanks of about 10 gallons in size. They are excellent for cleaning the tank as they suck up much of the dirt on the bottom of the tank. If you have ornaments in the aquarium you will find the fish will attach itself to them in all different hanging positions. Have at least one in every tank! And they are very peaceful toward other species. They generally sleep during the day or when the aquarium light is on.
Thanks for the comment Gene!
I agree that these are excellent fish but they are very fast growers and a 10 gallon tank is not suitable for the common pleco. They can reach up to 18 inches in size. If you want to get one and you have a smaller tank just be prepared to get them into a larger tank when the time comes. Or try to get a bristlenose pleco which should only grow to about 5 inches or so. Also, although we've never experienced it, we've heard reports of them becoming aggressive towards their tank mates. All that we have kept have always been very peaceful.

From: Leah via email
My plecos behaviour has changed in the last month. I've had him for over 2 years now. He survived (but didn't like) a move last july and his behaviour was similar afterward to that of before the move until about a month ago. Now s/he is almost always in hiding at the back of my 55 gallon tank and keeps to a trench dug into the gravel back there. I rarely see him/her out and about in the tank whereas once upon a time s/he'd be seen cruising about, sometimes playfully chasing other fish. There are no aggressive fish in my tank and it is not overpopulated. It shares the tank with guppies, mollies, one male betta, one cory cat and one yoyo loach. Prior to the move, the tank'd been established for about 4 years and most of the water made the move as well. Do they just kind of hibernate now and again? Is this indicative of illness or lonliness? Any insight would be appreciated.
Thank you - Leah
Hi Leah,
It's difficult to say what could be causing this behavior. They usually like to hide out during the day time and then scavenge around when the lights are out.
Some things you could try:
  1. Check your water parameters - if the nitrate levels are too high you may need to perform more frequent water changes.
  2. As your fish grows they will need more food and more space. If you are not doing so already, try to supplement your bottom feeder's diet with algae wafers that sink to the bottom of your tank. Your pleco will really like these. Your YoYo's and Cory cat will probably go after the wafers too.

From: Dave
Can you mix two different types of plecos?
The answer to this question depends on who you talk to. Assuming you have a large enough tank to house more than one plecostomus, it has been our experience that you may be safe doing so. Animosity towards each other may build as they grow in size. This fish gets very large, often times 12 to 18 inches or more. If you are going to have two plecos we would recommend having tank that is several hundreds of gallons or larger.

From: Pleco Lover
Can I keep a Bristlenose pleco in a 20 gallon tank?
The "general" rule of thumb is 1 inch of fish per gallon or two of water. But that could all depend on the type of fish we are talking about. Do you think a 20 inch fish would live comfortably in a 20-gallon tank? Me neither.

The Bristlenose gets to be about 5 inches or so as adults. So, if you have the space then it should do well in a 20 gallon tank. We are looking for pictures of the Bristlenose, so please send us a picture of yours if you get one! Very interesting looking fish.

From: TC - Sucking on fish sides
I've had my now 5 inch pleco for about a year. He shares a 29 gallon aquarium with a ryunkin, a fantail goldfish, and a large black moor. About a month or so ago I noticed he kept coming after the fantail. It seemed he was trying to suck it's side. In order to stop his aggresive behavior, I started giving him an algae wafer during the day, usually when I fed the other fish. That solved the problem. I'm not sure if there wasn't enough algae in the tank, but since it worked, I'm assuming that was the problem. Now, he's back to being his usual calm self.

From: Lori
HELP! My Pleco is sick! I have tried the following: His tank was very cloudy and had a foul smell approx. 3 weeks after a water change and about two months after the introduction of a new plant. I noticed that he had some tail rot, so I assumed he was stressed and performed another 50% water change. I also changed out all the gravel in case there was some sort of infection. He did not improve. I went to the local fish store (the employees were not very knowledgable) NOX ICH was recommended. I did not notice ICH, but the labeling says it will treat other conditions as well. It contains Sodium chloride 50% and malachite green 50%. I used 1/3 the recommended dosage due to their sensitive nature for the 3 day treatment. The water became cloudy and had a foul chemical smell. I have performed another 50% water change. The water is clearer, but it appears to have some dark patches on his skin. Is this bruising? He also is not attaching to the tank wall as well as he normally does. I don't know about his breathing as I have never paid much attention to it before. It appears normal and his gills look fine. ANY HELP? Thanks
Hi Lori,
The foul smell is most likely from poor water quality. Try to change the water and perform gravel vacuuming more often, especially if you have an overcrowded aquarium. This fish can be fairly dirty and keeping them means more frequent water changes. The tail rot was most likely caused by the poor water quality. Try doing a 25% water change once a week. This should go a long way towards getting rid of the foul smelling water and treating your fish.

You changed out the whole gravel bed? An established aquarium gravel bed contains loads of beneficial bacteria thats crucial in the aquarium nitrogen cycle. By removing the established gravel bed you will most likely have to re-cycle your aquarium. This will be extremely stressful on all of the fish in your tank. You will need to monitor your water parameters closely (ammonia, nitrite and nitrate) and perform frequent small water changes during the re-cycling process.

We only use medicines as an extreme last resort. Try this instead: use activated carbon in your filter to remove any remaining medication that was put into the aquarium. Gradually increase the water temperature to 80°F and give your fish the best water quality that you can by performing those weekly water changes. Since your aquarium will most likely re-cycle, you will need to monitor your water parameters very closely during this process and perform small water changes as needed until the cycle has finished. Good luck and let us know how it goes.

From: Jean Langford's Bristlenose Plecostomus
This first picture as you can tell is The Albino Pleco pair... the top one is a male and the bottom is of course the female. The males have longer "bristles" than the females. The last picture is of a male... notice the bristles! Hope this helps!
Albino Bristlenose Plecostomus Pair Bristlenose Plecostomus

From: Pleco
If you have a pleco, it is absolutely necessary that you have driftwood in your tank. They eat it, and it aids in their digestion.

From: Mountain Gal
My pleco is now over 12". I've had him a couple of years. At first I thought was kind of scary looking, but now that I'm used to him, I think he's very handsome, especially when he fans out. My concern was that he might be lonesome, but from reading comments, I see that they don't seem to mind that.

From: LJBroussard
I'm so happy to have found this site! Been keeping freshwater aquariums almost 50 years and enjoy the pleco comments. My pleco is 13 - 14 inches long and lives in a 50 gallon Amazon community tank. Key to tank health with a large, fast metabolism fish such as this is water quality. All my life I've done weekly 25& water changes in every tank (make sure new water same pH and hardness), fed variety foods, fresh veggies for the pleco, freeze-dried tubifex and frozen foods... good nutrition, meeting species needs (moving water and hiding spots) plus water quality is the key!

More Pleco Tips 1 | Pleco Tips 2

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