Plecostomus - Pleco Fish

Updated May 14, 2020
Author: Mike - FishLore Admin
Social Media: FishLore on Social Media

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.

Common Pleco

This fish 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 Photos thread.

As your fish 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 plec can get to it.

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

Pleco Plecostomus

Pleco Fish Care Details

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 they can be aggressive toward others of the same species.

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 species that are available. Smaller species include the Bristlenose, the Gold Nugget, Zebra and the Clown (linked in similar species below).

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

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

Diet / Foods : Opportunistic omnivores, but try to supplement their diet with algae wafers. They also will feed on any attached algae.

Tank Region : Bottom and the sides of the glass.

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

Photo Credit : Photos copyright

References :

Fish Forum : Pleco Forum

Forum Avatar :

Hypostomus plecostomus Hypostomus plecostomus

Pleco Comments and 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 type. 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 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 fishes 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 fish 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?
The answer to this question depends on who you talk to. Assuming you have a large enough tank to house more than one, 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 we would recommend having a tank that is several hundreds of gallons or larger.

From: PlecLover
Can I keep a Bristlenose in a 20 gallon tank?
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 plec 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 fish 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
This first picture as you can tell is The Albino 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 Pair Bristlenose

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

From: Mountain Gal
Mine 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 comments. Mine 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 them, freeze-dried tubifex and frozen foods... good nutrition, meeting species needs (moving water and hiding spots) plus water quality is the key!

From: Anonymous
I have not had much luck with them in my tank. I have 2 fantailed gold fish, and 2 guppies in a 20 gallon aquarium. Each time I get one they don't tend to live more than a week or 2 at most. At first I thought maybe I had gotten a sick one, but after 2 I've finally said the problem has to be on my end. Any help would be appreciated.
It could be many things causing their demise. If you keep your tank walls and the objects in it clean by scrubbing them with an algae scrubber then your fish isn't going to have much to snack on. You can always make sure they get what they need nutritionally by using Algae Wafers that sink to the bottom of the tank. As they get older they seem to hang out on the sides of the glass less and then you definitely will need to use the algae wafers. If you've been getting the common pleco, they get really big (18 inches - 46 cm) and a 20 gallon will be way too small for them. Look into the Bristlenose which should stay much smaller.

Check your water parameters with a freshwater test kit and write us back with what you find out so we can diagnose further. More specifically, check the ammonia, nitrite, nitrate and pH levels.

From: Vincent & Gina
We have tried them in our 10 gallon tank. The tank seems very clean, we have an outside filter. Could they be starving?
They may be not getting enough to eat and you could make sure they are getting enough by giving them sinking algae wafers. You have a bigger problem though. The common gets very large (18 inches or 46 cm) and you need to keep them in a much larger aquarium - 55 gallon or larger.

From: Abi Morris
I've had my fish for about 5 weeks now and he seems really happy, but I've noticed his underside seems to be getting much lighter in colour. Is he sick or is this normal? Please help!
They can change their color slightly from time to time. Check your water parameters (ammonia, nitrite, nitrate, pH) and make sure that they are within acceptable ranges.

From: Snakes
I have a 9ft long X 3ft wide X 4ft tall tank with 4 commons, 5 Rapheal Catfish, 6 Tinfoil Barbs, 10 Silver Dollars, 4 Convicts, 4 Firemouths, 1 Jack Dempsey, 1 Green Terror, 1 Red Terror, 1 Maganese, 1 Red Devil, 1 Texas, 2 Oscars, and 4 Arowana's. My 4 commons are doing just fine since they all have plenty of space to call their own. I feed them shrimp pellets, algae waffers, and cucumbers. They appear to be very happy.

From: Tank
We are currently on our 3rd common pleco. Unfortunately, I believe our 1st two starved to death as a result of not knowing to supplement their diet with algae tablets, shrimp pellets, par-bolied zucchini pieces as well as romaine lettuce. I am happy to say that our current fish is doing well, and has grown from 2 inches to 8 inches in almost the 1yr. that we acquired him. They are a bit more work than alot of fish as their tank should be "vacuumed" on a weekly basis to keep the water from becoming polluted and an unhealthy enviroment for all, but they are worth their weight in gold.

From: Joel
I got my common pleco in my 55 hexagon tank. I've had him for half a year now and I'm happy to say he has grown from 3 in to 8 and a half inches.

From: J Dixon
Can I URGE all of you to read up on your fish (especially plecos) before you buy them! Make sure you have enough room for them when they are full grown and that you are feeding them correctly! Also... as with any tank make sure you check the water parameters at regular intervals especially if you have just set up a tank. A lot of plecs are really expensive and can grow very large. If you lose one because of no forward planning, that is a lot of money wasted and a beautiful fish killed because of your ignorance!

I have a lot of plecs including an adonis, a breeding pair of bristlenoses and a royal. These live in a 105 gallon tank and are happy but always remember to give a lot of hiding places if you have a lot (to stop fights) and to regularly check their bellys as you can tell if they have not been eating enough because they go inwards. A healthy plec will have a flat(ish) belly. If it is swollen it may have an infection. When you have found a plec you like on the internet or book e.t.c and have read up on it and made sure it is compatible in your tank. Make sure you choose one that does not have an inward belly. Where plecs are caught they are often not fed for weeks and one that has had nothing at all by the time it is in the pet store is likley to be almost dead. Look for possibly bits of food (cucumber? algae tabs?) in the tank and look at their bellys. Thats all I can say to help. Hope it has been informative.

From: RedTailCatLover
I have an odd pair of fish in a 300 gallon tank, my first is a large redtail catfish, next is a large sturgeon, and then a common who is about 20", he's huge. They get along very well, but a tip: at larger sizes they get to be very messy, and they poo all over the place, so the water quality can become poor quick, so if you plan on keeping them with other bottom fish and letting them grow together you will need to check the water almost daily, at least weekly, and perform weekly water changes of about 25 percent. Just thought I would let people know before they get into something they can't handle.

From: Shelli
A friend gave me a rather large plecostomus when he got rid of his 55 gal tank. I had a 3000 gallon back yard pond that I thought he would like to live in not knowing anything about them. Now it is getting colder and I realized he might not be able to hibernate with the other fish in the pond. I can't find any information on whether they can withstand a Kansas winter in a 3000 gallon pond. He is approximately 16" in diameter.
We've read some reports of folks keeping them successfully outside all winter and others not being successful in doing so. Kansas winters can get really cold and this fish needs warmer temperatures. It can't be good to keep it exposed to lower temperatures for long periods of time. We would advise bringing your pleco indoors for the winter.

From: Scott
This is my 2nd favorite fish because you bearly have to give it anything. I just feed mine algae wafers every once in a while but he seems to get bigger even when I don't feed him. This is a good chioce for a beginner with a large aquarium.

From: Kate
Bristlenose plecos are quite easy to breed if you have a big enough tank. Also, not all plecs come from South America, e.g. zebra and sunshine plecos come from xingu, brazil. Sorry if I seem abit picky but there you go, thats just me when it comes to plecos!

From: Ashley
Mine is about 7 to 8 inches and has been very peaceful with my other fish for a year and a half. But lately he has become aggressive towards the other fish, and will try to hold on to their sides with his mouth even though they are larger (by mass not length). He has enough food, he eats the algae, and he gets cucumber, and sometimes pellets. Do you know why he's doing this, and anything I could do to stop this without getting rid of any of my fish?
Although infrequently, we have heard reports of this happening with them. It's probably best to remove the pleco from this tank. Try to trade it in at your local fish store for something else or if you can't relocate it to another tank, give it away to the store or a good home.

It's hard to say why it's doing this, perhaps it's not getting enough of something in its diet or it has developed a taste for the slime coating on the sides of fish. You could try to prevent this from happening by increasing its diet by feeding it more algae wafers and cucumbers, especially if there isn't alot of algae in the tank for it to graze on.

From: Trey
Hey I just got a common pleco about 2 inches long and I'm having some water cloudiness problems. He's in a 10 gallon tank with 2 goldfish, each about 1.5 inches. I've had the tank 2 weeks and after just a few days the water starts to get cloudy. How should I go about fixing this?
Yikes. Goldfish need at least a 10 gallon each, so at least a 20 gallon for two. This fish gets way too large for a 10 gallon tank. Since you say the aquarium has only been setup for 2 weeks, it should be going through the aquarium nitrogen cycle. You can prevent these problems from happening by researching your fish before buying them and reading up on the nitrogen cycle, linked to in the previous sentence.

From: Fishie
I have found that they LOVE cucumbers! They make neat onion rings out of cucumber slides stuck to the wall of aquarium!! They clean out the remaining cucumber as it floats in the water and all that remains is cucumber skin! If you are out of algae, this is the cheapest and easiest pleco food.

From: Heidi
More than 12 yrs ago I had some other fish with 2 plecos and one day, I guess because they were hungry (I too didn't know about food for bottom feeders) they started eating the fish flakes. One was about 6 inches and the other 4 inches. The large one started first and later the other joined in. They would come to the top and stick their mouths partially out of the water to syphon in the flakes that were on the surface. It was somewhat entertaining to see them in this vertical position sucking in their food until they became full.

I miss them. Unfortunately, I couldn't keep plants with them because they were constantly digging them up and probably eating at the roots I suppose. I gave up after 6 plants.

From: Toast
What I've found exciting about Bristlenose Plecos is that they munch happily on black beard algae. Surprising, as most of the research I found suggest that only Siamese Algae Eaters eat the stuff. I watched my roommates fish take vast swaths of BBA off of his glass. A staple for any medium to large sized aquariums.

Still have questions?
Jump on the forum and ask your question!
Go here: Pleco Forum

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