Last update: March 15, 2024

How to Identify and Kill Planaria Worm The Easy Way (In Just Days!)

Are your shrimp dying mysteriously?

Have you noticed strange, flat worms sliding around your aquarium?

If you answered yes, then you might have a planaria infestation.

You’ve come to the right place! Because today, I’m going to tell you how to get rid of them for good! First, ensure you have these products to effectively eliminate planaria and other parasitic infections in your aquarium:

What are planaria and how do you identify them?

Close-up of a single planarian on a leaf in aquarium

Planaria are a variety of flatworm that are considered a pest by the majority of aquarists.

These flatworms can quickly multiply in number and, as you will soon learn, can be dangerous to other members of your aquarium.

But before I continue, I just want to quickly comment on how to correctly refer to planaria:

  • A single flatworm = planarian
  • A group of flatworms = planaria

Trust me, it’s important to know this, otherwise the rest of this guide is going to get confusing quickly.

Planaria are possibly the weirdest worm that will ever visit your aquarium. Their unusual traits make them widely studied in the scientific community…

Perhaps the weirdest thing is when you cut one. Let’s say you cut a planarian into 5 pieces. It will regrow into 5 different planaria – this is why it’s a bad idea to crush any planaria you find in your aquarium.

Stubborn, huh?

As you might have guessed, removing planaria from your aquarium can be a difficult task. But don’t worry, I’m gonna share a secret weapon to eradicating this troublesome flatworm later in the guide.

First, you want to make sure that it is actually planaria that you are dealing with.

Planaria are small. Very small. Measuring around 0.1 to 0.6 inches, so they are easy to miss.

Planarian flatworm on Marimo moss ball with shrimp on top

In fact, you likely won’t notice them at all unless they grow in number or bravely slide their way over your aquarium glass.

Planaria gliding over front glass of aquarium

Not a pretty sight, huh?

And, if the name flatworm didn’t give it away, they are flat. Like someone had a small earthworm and went at it with a rolling pin.

There are actually two types of planaria flatworm commonly found in aquariums:

  • White planaria (Procotyla)
  • Black and brown planaria (Dugesia)

To make things more confusing, some types of planaria can change color according to what they eat. Colored flakes, for instance, can turn a planarian a lovely shade of pink.

Besides the color, they are nearly identical in appearance.

Once you know what to look for, the unique features of planaria make them difficult to confuse with any other flatworm.

Unlike other flat worms, planaria have a distinct triangular-shaped head.

You can see it clearly in this close-up of a planarian…

Close-up of planarian triangular head

This is the best way to identify planaria without using a magnifying glass – the arrow like head is visible to the naked eye.

Unfortunately, when planaria squish up, it can be difficult to see this shape.

But don’t worry, there is another way you can identify planaria…

However, you’ll likely need a magnifying glass to see these. Don’t have a magnifying glass on hand? If your phone has a decent camera, use the macro-mode to take a picture and zoom in.

What you want to look for is the cross-eyes. Yep, this shovel-faced pest is also cross-eyed. Well, at least it looks that way. At the tip of the head are what look like two eye balls with pupils facing each other – you can see it in the above picture!

The pesky planarian is often confused with another flatworm, rhabdocoela. Rhabdocoela is similar in size and color to white planaria. However, when compared side by side, the differences become clear.

It’s all in the shape of the head…

Planarian vs rhabdocoela flatworm compared side by side

On the left, you have a planarian – its tell-tale trianglular head makes it easy to spot. On the right, you have a rhabdocoela which has a rounded head.

It’s important to know which is which because rhabdocoela do not respond to many treatments that will kill planaria outright.

What causes planaria to appear in your aquarium?

It’s going to sound strange, but chances are that you put the planaria in your aquarium yourself. You probably got them from your local fish store, who likely got them from one of their suppliers.

Unfortunately, no one is to blame – dealing with planaria is just a part of fishkeeping.

You see, planaria are expert hitchhikers. These sneaky little flatworms hide away in rock crevices, on plants and even attach themselves to fish.

Once inside your tank, planaria reproduce fast. And, all it takes is a single flatworm. You see, planaria can reproduce asexually, meaning that one worm can soon become hundreds.

And if you do see hundreds of planaria, then chances are you had a helping hand in the matter…

Black and brown planaria flatworms feast on waste. Biofilm, uneaten fish food and even poop – it’s all a tasty meal to planaria. If you notice these planaria, it’s often a sign that you are not maintaining a clean tank.

If you are nodding your head, rinse your filter, grab your gravel vac and perform a water change – and get it in the habit of doing it regularly!

White planaria, on the other hand, eat small worms, shrimp and even live foods such as daphnia or bloodworms. If your tank has an abundance of food for white planaria, you will soon see them multiply in number.

Are planaria dangerous?

Planarian worm next to shrimp on glass of aquarium

Brown, black and white planaria are dangerous, but each in their own way.

White planaria are aggressive predators and are particularly dangerous to shrimp. Shrimp eggs and baby shrimp make a tasty meal. However, it is not unheard of for hungry white planaria to go after adult shrimp too.

While brown and black planaria do not hunt shrimp, they are more than capable of killing them. You see, planaria move on a slime trail, just like snails. However, unlike snails, the slime that planaria release contains a toxin that is deadly to shrimp.

Speaking of snails, if your tank has snails, like ramshorns, planaria are a big threat for the same reasons. And, they love snail eggs too!

Planaria attacking snails in aquarium

Anyway, back to the slime…

If this slime touches the belly of your shrimp, or if planaria crawl under the exoskeleton, it will stun your shrimp, and then planaria will happily eat it alive. Check it out:

If you own a shrimp tank, get rid of a planaria infestation as quickly as possible!

Which brings me to my next point:

How do you get rid of planaria?

Planaria is notoriously difficult to remove from your aquarium. If you miss a single flatworm, it will multiply into many.

It is for that reason that I do not recommend using a glass trap to get rid of planaria.

You know the ones with the angled openings that allow worms to squeeze in while keeping shrimp out?

Like this one…

Glass planaria flatworm trap for aquarium

There’s no arguing that they work, but it relies on your planaria being hungry. If the planaria are not attracted to the bait you placed inside, then it’s as good as useless.

And again, there is no guarantee that you are going to capture every single planarian in your aquarium.

If you still insist on using a planaria trap, grab this one. I have personally tested it and can confirm it’s well made and more than capable of capturing planaria – bait it with raw chicken!

But for the rest of you who just want a quick and simple way to treat your planaria infestation, I have an amazing product for you…

The ultimate planaria killer

Panacur C Fenbendazole to kill planaria

If you have ever treated your dog for worms, you will be fully familiar with this product.

I was actually introduced to this product by a friend at my local fish club who, used this shrimp-friendly way to kill hydra.

And, it works just as well at getting rid of planaria!

The secret ingredient? Fenbendazole. It will eradicate a planaria infestation in just a few days. It’s like a planaria nuke!

Follow these steps to get rid of your planaria problem for good:

1. Buy your Panacur C. Panacur C comes in different sizes. I personally recommend buying the packet that has 3 x 1g bags (this one), as it will make measuring easier – a little goes a looooong way.

2. Remove your chemical filtration Your carbon filter or purigen can remove the Fenbendazole from the water before it has a chance to work its magic – remove it and replace it after treatment is finished.

Oh, and be sure to remove any snails you want to keep. Fenbendazole can be lethal to those too! Malaysian trumpets and Nerite snails, in particular, seem to be affected.

3. Measure out your Panacur The dosage is 0.1 gram for every 10 gallons. So a 60 gallon tank would need 0.6 grams of Panacur C. A gram scale will make measuring incredibly easy – I use this in fish keeping all the time to measure out doses. Sprinkle this powder into your tank.

If you don’t have a gram scale on hand, here is an alternate method: Dilute the whole 1 gram packet in 500 ml of RO/DI water. You then dose 50 ml for every 10 gallons of water your tank holds. So a 60 gallon aquarium would be dosed with 300 ml.

4. Redose Wait 48 hours (2 days) and reapply the same dose.

And just like that, your planaria problem is cured.

Once you are confident that all the planaria are dead, there is just one final thing to do. Grab a good gravel vac and remove as many of the dead bodies as possible. Follow up with a water change.

Next, you want to use your trusty aquarium test kit and closely monitor your ammonia levels over the coming week.

This is particularly important if your aquarium was overrun with planaria. You see, those bodies are going to break down and as they do, they release ammonia into the water. So, you want to catch it fast if your ammonia levels spike.

Woo! You won the battle. You are now in the clear, and your tank is a certified planaria-free zone. Feels good, right?


As you see, planaria are stubborn little flatworms that are dangerous to the tiny critters in your tank.

And, it can be heart-wrenching to see them wriggling all over your aquarium glass, as they quickly take over.

But they don’t have to be feared!

By following the instructions above, you can be rid of them for good in a matter of days.

Got a planaria-busting trick you want to share? Let me know in the comments below! Also remember to purchase the products to effectively eliminate worms and parasites in your aquarium:

Ian Sterling

Ian Sterling, founder of, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website,, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.

Comments (122)

Thanks for this. I had a wonderful population of burrowing snails, that I discovered around the time I discovered planaria in my tank!

A couple months later I noticed I cannot find any burrowing snails (though I still have rams horns).

Guess now I know why!

I have planaria in my tank with very expensive piece. Zebra. How can I kill all planaria without harming my piece and discus

Hi Paul,

My suggestions are mentioned in the guide above. Manual removal of planaria, such as using traps is guaranteed to be harmless to your fish. However trapping every last flatworm is unlikely and you will need to use it on an ongoing basis. As always, research anything that you plan on adding to your aquarium to see how it will interact with your unique setup.

Hi Oswaldo,

When used correctly, planaria zero is considered to be fish safe and many hobbyists, including myself, have successfully used it to rid themselves of planaria. If you are unsure, I would discuss this further with a Flowerhorn expert.

Hello Sir,

I have a bare bottomed discus tank which I keep meticulously clean. Yet I have got a white worm like pest in my aquarium. They are no more than 5mm long and as thin as a human hair. They crawl, not slide up the glass, and can become free swimming, they wriggle through the water like a small snake. I have got a video of them which I would like to send you to help me identify what they are, and how to get rid of them. This is important to me because this is a 130 litre discus breeding tank, and I see them invading the discus eggs on the breeding cone which frustrates the adult discus, and annoys the he’ll out of me.

Thank you in anticipation.

Hi Steve,

If it can wriggle through the water, it likely isn’t planaria – these things are surface huggers. It’s possible what you have is commonly referred to as a detritus worm.

I highly recommend signing up to an Online Aquarium Forum and posting your info and video there, there is no doubt that someone has experienced the same infestation and will be able to identify the pest right down to it’s scientific name.

I have a fish tank with a sunfish, the sunfish died, when i looked in the mouth of the sunfish I saw all of those planaria pack in the mouth so water couldn’t get to the gills, is this common with sunfish?

Is this safe for discus tank containing rummy noses, blood fins, sterbai corys, balloon belly rams, congos, otocinclus cats, and cardinals? I’ve searched online ad nauseum for interaction with discus and came up empty. Many thanks for your help!

Hi San,

Unfortunately, I have no first hand knowledge as to how this would react with discus. While I have used it multiple times without any negative affect on my tanks, discus were never involved. If you want to put your mind at rest, you could try dosing with Panacur instead – the active ingredient, fenbendazole, will also kill hydra. There are many reports of it being safely used with discus. In fact, it’s also suggested as a treatment for de-worming discus.

Well I started a new tank with plans for a planted nano with shrimp included and a landscape to look like they are in a forest, I have 2 other planted tanks that are about 2 years old but I really put some thought into this one! Bought a few plants from a local pet store and eventually these jerks poped up on my glass, just a few here and there, but I don’t want them with my shrimps at all! I plan on removing my nirite snail and doseing tank but I am wondering how to tell if fish have planari hitchiking in them? Would they be stuck to the outside of the fish or more in the gills?

Hi Breeanna,

Planaria can slide inside the gills of fish or on the body. The surface ones should be easy enough to spot when purchasing. As for the ones hidden in the gills, this would visibly cause the fish stress. You should already avoid buying fish that look stressed.

Can you use this during cycling with a sponge filter? I have a pond snail and no where to put him but I’m not that attached.

I recently ordered some plants that came with snails, and I made a small ‘jarrarium’ for the snails. The majority of the plants are still in quarantine but I did move two into the jar after separating them out for a few weeks.

I recently noticed little wormy things that I thought were planaria until I read your post (But was positive they didn’t look like the Rhabdocoela in my main tank.)
However, their bodies are thinner than the images you show here, and their head is a circle – not a spear shape.
They also often seem to have a dark patch around their midsection which I assume is food in their gut.
Are these the brown Planaria, or something else entirely? Could they be leeches?

Tried to get good images but they’re pretty tiny:

Thank you 🙂 I’ve been really nervous about these little things. Really glad to hear it’s just a detritus worm I’m not used to.
Thank you again!

Looking at the pics they appear to be planaria not detrius worms. If they seem to just fall when you detach one from the glass they are more likely planaria but if they wiggle quickly then they are worms.

I just added api aquarium salt to my tank and i cant say its working pretty good for me.
Not sure how to add pictures yet . After a hour or two it showed me i had an infestion. I’ll upload pics when figure out how to.

Thank you for the wonderful information. Do you have any suggestions regarding possible hitchhikers on/in snails? I have had a planaria outbreak start a year ago . I’ve been using traps and I get the numbers down but have never eradicated them. Recently, they are now in 3 of my 6 tanks. Based on your above information I plan to use Planaria Zero, once acquired. The tanks contain snails which I will remove for treatment. I know most hobbyists aren’t particular about their snails, but I am. I currently keep approximately 9 different species and 17 different varieties of snails, ranging from the common Pomacea Diffusa , to more exotic such as Black Devils, multiple rabbit varieties, pagodas etc. Based on your article, I’m thinking that may be how they came in and passed between tanks. I’m thinking they hitched a ride in a shell. Do you have any suggestions on treating the snails to rid the planaria without killing the snails? I’ve already lost several and breeding has almost halted or I thought it had. Now I think the planaria ate the eggs. I’d appreciate any advice!

Hi Meg,

I know some aquarists use PraziPro (active ingredient: praziquantel) when quarantining freshwater snails before adding them to their display tank.

PraziPro can kill both Planaria and parasites. Just make sure the solution is pink before using it – if it has been frozen, say during transport, it goes clear and won’t do anything.

I have personally seen one fishkeeper successfully use PraziPro with rabbits and mystery snails, so I believe it to be safe for the larger varieties. As with any chemical you add to your tank, I highly recommend researching it further first – all tanks are different, after all.

Will planaria kill mystery snails? I just found out i have the brown planaria in one of my planted tanks. I going to assume they are in all of my tanks. I have bought mystery snails on and off over the last nine months and they have all died on me after 2 or 3 months. I have no clue why they all died very slowly. So i am wondering if it was t by e planaria.

Hi Sandy,

If you have eliminated all other causes, such as poor water quality, say your tank isn’t cycled or your water is high in ammonia (use an aquarium test kit) then it’s possible planaria are responsible for the deaths of your snails.

Hi Gina,

You likely are not from the USA then. No-Planaria is another product commonly used in Europe, I believe it to uses betal nut extract. You could try that.

Just wanted to give a big thumbs up to this post and another recommendation for No-Planaria for eliminating Planaria or Hydra. I see a lot of people nuking their tanks with all sorts of meds and I believe as a hobby we should move forward by using safer and more effective methods. When people say they just nuke their tanks with dog medicine I either assume they are stubborn, misinformed or new.

Thanks for your feedback, Andrew.

I completely agree with your your thoughts. Unfortunately, dosing tanks with synthetic chemicals has become normalized in the fishkeeping hobby.

I read that increasing the temp of the tank to 35C for a few hours may work (after removing fish of course). Would you recommend this? I was worried it may kill the bio filter but I did some research and it turns out they only die at close to 47C. The only negative I can imagine is the plants not enjoying the conditions but unless someone set it this high for over a day i doubt it would affect them too much unless it was a very sensitive type.

Hi Courtney,

I have no experience using temperature to kill planaria. If you are raising the temperature this high I assume you have no fish in your tank? Another concern with raising the temperature is that you may trigger an algae bloom (often green aquarium water) that will require intervention even if you drop the temperature back.

What dosage did you use for the no planeria? I purchased and dosed but have seen no effect after two dosages and 5 days so far

Hi Brian,

I used the following:

Day 1 – add 1 spoon per 6 gallons of water in your aquarium
Day 3 – add 1 spoon per 6 gallons of water
Day 4 – perform a 20% water change
Day 10 – add 1 spoon per 6 gallons of water
Day 11 – perform a 20% water change

Hi Janez,

Having accidentally touched hydra with bare hands on more than one occasion, I can confirm from experience that these are harmless to humans.

I had a healthy, established fish tank and then I bought some amano shrimp from my LFS. Within days, I had a planaria outbreak. They were very, very small, moved quickly over the glass, and only came out at dusk or night.

I tired everything to get rid of them: removed all the live stock, changed out the water, put in a new filter, added salt, raised the temperature, replaced the substrate, cleaned the tank out with bleach. Nothing worked. When I put the tank back together, the planaria came back as well.

I then purchased and used the No Planaria product. It was hard to find. I got it from an online fish supplier for $36.00. I followed the instructions and was very conservative with the medication. It left the tank water very cloudy.

Well, my Betta got very, very sick and almost died. It took weeks for my fish to recover and he is finally doing better. That said, it is two months later and the planaria are back (or still there).

I am not going to use the No Planaria product again. I’m just going to live with the Planaria as is while continuing to keep a clean tank. So, if you plan to use No Planara, be very careful.

Hi Carri,

I really appreciate you sharing your experience. While I have been unable to replicate your process with my use of it, like with every product we add to our tanks, it makes sense that there is room for things to go wrong, especially when we all add different chemicals, substrates, foods etc. I’m glad to hear that your Betta pulled through!

I have 4 tanks going now. In one, I have Planarian and they killed my Nerite! Fortunately, I have no shrimp in that aquarium. I have another tank (3 gal) with Hydra infestation (last time I buy anything but plant cultures.

Another tank has two guppy fry, which were all we could save from Mom and the corydoras. That tank also has an expecting Platy, which is of course separated from the guppy fry.

Finally to my questions: 1) While I have no signs of infestation in the platy/guppy tank, should either hydra or planaria rear their ugly heads, is Planaria Zero likely to kill fry? 2) Somehow I suspect that sharing if nets and possibly even the liitle jars I use for water samples is a potential route of infection; should I use different nets, jars, etc. for different tanks? While I await a reply from someone, I will be buying separate implements for each tank just as a precaution.

Hi Susan,

Since Planarian are hitch-hikers, the easiest way to infest your tank is to accidentally transfer them when sharing equipment between tanks. Your decision to buy separate implements for each tank was a wise one! I have only used Planaria Zero with adult fish. Since fry are more sensitive, I do not know how they would react.

Hi! Thanks for such an in-depth article. I’m currently in the business of raising ramshorn snails – I have a multi-layered recirculating system (six 2-gal tanks first level, feed into three 10 gal tanks, feeding into 150 gal sump). I noticed today one of the top layer 2 gal tanks was infested with planaria, interestingly enough it seems to only be that tank. I have since removed snails to a quarantine tank and stopped water flow to the infected tank/emptied the water.

After watching my quarantine snails it’s clear the planaria are disturbing the snails as they withdraw once the worms touch any part of their soft body. I have tried prazipro with little success. Do you think there’s a possibility to find a secret spot in dosage using the product you suggested that could effectively kill the worms but leave my precious snails safe and sound.

Thanks in advance for any advice you can share on this tricky issue.

Hi Ivanna,

That sounds like a really tricky scenario. I’ll admit that I do not have any experience using betal nut extract at a half or weaker dose. If you wanted to experiment, you could try adding a single planaria and a snail to their own tank and monitoring what happens – if you are in this for the long term, it would be good to narrow down what works. But I do not recommend blindly testing on an entire tank. I wish I could be more help here.

Hi Andy,

Rhabdocoela can go away on their own if you “starve” them of food. They often explode in numbers in non-maintained tanks or where overfeeding is caused. Since they are harmless, I tend to leave them to co-exist with my tank, they help keep the tank clean!

The last planaria infestation I dosed with Panacur C also wiped out the Rhabdocoela as well. I’m unsure if Planaria zero will do the same – I used to recommend that over Panacur but it can be difficult to track down and shipment sometimes takes weeks.

I have read your article and appreciate the information on these worms. I have a newly 10gal tank I’ve set up for shrimp and I’ve noticed one of these on the glass then go down into the gravel. I’ve read through all the other comments but didn’t see a comment about adding Panacur in shrimp tank. Is it safe for shrimp?


Hi Robert,

Excellent question, from personal experience, I found Panacur C to be shrimp safe – tested it on cherry reds and amano. Other fish keepers widely report success too on aquarium forums as well.

Hello, my tank is currently done cycling with two male guppies. Can I dose Panacur while fish in the tank with life plants too?

Hello, ive recently notices these little white worms in my turtle tank. It contains a softshell turtle, a musk turtle, and 2 sliders , along with live plants and snails. Is the treatment safe for turtles? Or should i remove all live animals before treatment? Thanks

Hi Brandi,

Unfortunately, I do not have any experience with turtles – I’m purely a fish kinda guy. Can anyone with a turtle tank weigh in and help?

Hi Brandi,

Sounds like you either had detritus worms or rhabdocoela those fish don’t eat planaria. That’s good news though, I’m glad you found a solution!

I’ve just noticed these white worms in my tank and my fish have dying and some are coming out in white spot is this down to this I’m treating the water but nothings happing do you have any suggestions on how to clear it thanks

NO need to publish on page, this comment is just for the sake of sharing with you, this was very interesting to read. My daughter just did a bio lab experiment where they split this type of worm to make it grow two heads. I had never heard of this worm, so in “googling” it your link popped up. All new to me. As i stated this page is very interesting and informative including the comments and questions at bottom of who are dealing with these tiny critters. Since I have always appreciated viewing well kept aquariums/tanks, especially with shrimp and such, i guess it made the topic that much more intriguing. Thanks.

Hi Julie,

That experiment sounds very interesting! I think the only thing more scary than planria already are would be a two-headed version!

Thanks popping in to comment!

How about for scaleless fish? I have an axolotl. The tank has been up and running for awhile. I just had done a 75% water change and then boom a bunch of worms :/ I had gotten some new plants about a month of two ago, they came with a healthy batch of pond snails 🙁 but nothing more than that. Do you think I should just remove all decor and throw plants out and just water change a bunch? Would that help…or do I need chemical treatment? If so should I put my axolotl in a 10 gallon holding tank while I do that? I use a sponge filter so I am assuming there would also be some in there to right?

Hi Julia,

Unfortunately, I do not know a whole lot about axolotl. On the worms front, are they long and thin? A water change can often push water around the tank and send detritus worms out of hiding. Detritus worms are safe.

Whether they are detritus worms or planaria, a water change and removing decore won’t get rid of them.

Hi, can I use your blog for my academic writing?? How would you like me to cite your blog if I am allowed to do so?? Thank you very much. I find the information here quite useful.

Hi Belle,

Absolutely. If you can link back, great. Otherwise, however you see fit. My main concern is sharing good information with everyone.

Somehow internet shut down on me … so my question on Panacur C … never mind ???? there’s no easy way to get rid of them when the planted tank has nerites, fish and shrimps????

Thank you for posting this information! My tank has an aquaclear power filter, with a sponge, active carbon, and BioMax beads layer. From what you wrote, I know I should pull the carbon (and will replace it with a new one when the tank is done being treated). But, I was wondering if the sponge and/or BioMax beads should also be pulled?

Thanks again!

Hi Skratazoid,

The beneficial bacteria lives in the sponge and biomax. Ideally you would rinse the sponge off in siphoned tank water so as to keep whatever benefical bacteria is inside.

Hey I have the worms ur talking about the black ones with the triangle heads I was wondering if you know do hot water kill them. I’m gonna clean my tank but I wanna get them off the sand to and if scolding hot water kills them I can just boil some and clean the sand in it

Hi Eric, good question, I have no experience using boiling water to kill them since that would involve emptying my entire tank. I would be very surprised if they could handle boiling water.

Regarding the recent question about boiling water’s effect on planaria: I have been using hot (140-150oF) running tap water to remove them from my plastic siphon hoses and rectangular plastic fish boxes I use to put a dirty filter in to prevent spillage/drips. After using the plastic fish box to handle the filter, I often have a dozen or so planaria that have fallen from the filter element. Rinsing with water that is less than hot will not dislodge them but they let go if it gets hot enough for long enough. I rinse the hoses over a white sink and as the hoses heat up, suddenly there will be a shower of panaria coming out as it gets hot enough to dislodge them. They go down the drain, so I don’t know if they are dead or stunned.

One might use caution in heating a glass aquarium…sheets of glass can crack under uneven and drastic temperature changes.

I have 7 tanks running and several of those tanks in various stages of infestation. I have treated the worst tank with fenbendazole. Prior to treatment, I removed the H. rasboras, snails and (almost) all the cherry shrimp, then placed two 2-1/2″ to 3″ goldfish in the heavily planted tank. They grubbed and rooted around for a couple days and seemed to get almost all of the planaria. Amazing how enthusiastically they ate them. I took the goldfish out and treated the tank. I’ve only seen a couple crawling around and got a few out of the filter, and I’m due for the 48 hour retreat tomorrow morning. I’ll probably let that stand for a day or two, then start with the water changes.

Thank you for your detailed article! I remember planaria from biology class a few decades ago, but didn’t realize how dangerous they were in a tank, nor how quickly they would multiply. I very much appreciate your advice.

Hi Ed,

Thanks so much for sharing your experience on the effects of heat on planraria. Your caution of heating up a glass aquarium is also well founded.

It sounds like you are trying to overcome a big infestation. I wish you the best of luck with your battle however, I’m sure the Fenbendazole should do the trick.

By your experience, how soon is it safe to return snails into the tank post treatment? I have Ramshorn snails, Red-rimmed melania and Acuta bladder snails in there.

I’m still on the fence about using chemicals to solve the infestation. There are Zebra plecos in that tank – a fairly sensitive fish. They also go eat only after light gets turned off and I suspect the planaria are eating their food beforehand, so there is no hope of reducing population by starving them. I’m trapping the pests for now, but would be much happier with solution, that can get permanently rid of them. If anyone has any experience of using Panacur in tank with zebras, or any other Hypancistrus, please let me know.

Hi Katy,

I asked my local nerite expert. His process is 3 large water changes (50%+) adds a carbon filter and waits a day before reintroducing his nerites.

Hi Ian!
I have pet snails and I recently noticed these tiny white worms. Yesterday I saw 2 bigger ones and I confirmed that they are indeed planarians thanks to your guide. Now I am getting ready to get rid of them. As you have mentioned, the panacur C is harmful to snails…so I will take them out and put them in a quarantined tank while I treat the infected tank.

My question to you is when will it be safe for me to reintroduce the snails back into the treated tank.

Thanks in advance !

Hi Linh,

The snailkeeper at my local fish club does 3 large water changes (50%+) adds a carbon filter and waits a day before reintroducing his nerites.

Tonight I noticed an out break of these white worm looking things that were attached all over the aquarium walls. I’m not sure if they had a triangular head though as they were very small for me to see that detail. Along with this outbreak I also had an infiltration of those annoying brown snails and this all happened after adding new plants and 4 shrimp to my fish tank. I went to my local pet store and I bought new everything, new 10 gallon tank, new gravel — in this case I decided to try sand now, new filter, new ornaments, new heater, the only thing I kept the same was my tank light and I cleaned that sucker too anyway with Clorox wipes. I was so paranoid to touch those little suckers, I wasn’t sure if they were harmful to humans? I wore gloves the whole time and I put all the contaminated snail infested and worn infested items inside a trash bag and put them outside in the bin. So, are any of these worms that can come from fish tanks be bad for humans or are they harmless? Thanks in advanced. 🙂

Hi Cassie,

Generally speaking, Detritus worms and Planaria will not harm humans if they touch your skin. Even so, I personally use gloves when dealing with them.

So the actual ingredient that kills the planaria is the fenbendazole?. So is it potentially just as likely to work if I was to buy straight fendendazole?. Or any other pet dewormer containing it?. Just purchased a 35g planted cherry shrimp breeding tank for a deal that seemed too good to be true. Now we know why, got home and noticed the little buggers everywhere. Will it effect the plants in the tank?. Would it be easier to just flush the whole tank and start a new one?.

Hi Alex,

That is correct, the active ingredient is fenbendazole. Unfortunately, I have no experience using straight fenbendazole and could not tell you how to dose it.

When dosing, it shouldn’t have any impact on your plants. Whether it’s easier or not depends on your situation. If you are happy to strip the tank back and start again, then that’s the easiest and cheapest process. However, if it’s already set up, then you will need to cycle the tank again.

The Fenbendazole concentration is 22.2% in Panacur C. To match that in pure Fenbendazole, use only 22.2% of what has been recommended.

If the desired dosage for the 22.2% concentration is .1 gram/10 gallon, the pure Fenbendazole would only require 0.0222 grams/10 gallon. (0.1 x 0.222 = 0.0222)

I have guppies in my 10 gallon tank. I was wondering if I’m going to use panacur c, is it safe to leave the guppies in the tank or should I take them out? Also if I were to leave the guppies in the tank and I use Pana cur c would this product help to get any internal parasite out of the guppies?

Hi Chad,

The guppies should be fine. As for the internal parasite, it’s hard to say and would entirely depend on the parasite inside.

Very informative.
Thank you for giving back to the hobby you have enjoyed for so many years. It augers well for the fish keeping community.

I have these inside my body. I ran into a sticker bush on side of road and ever since I have had a few different little critters. How can you get rid of them in humans? Please help

I have been to doctors. No one will help me. Can u tell me what will kill planarian flatworms in a human?.

Hi Lisa,

Unfortunately I cannot. I am not qualified to provide medical advice. If what you are saying is true, it is serious and requires medical intervention.

Food grade Diatomaceous Earth kills parasites, worms and a host of un wanted buggers in the digestive system.

Lisa, I’ve read that a couple things will kill in humans.. Albendazole, Praziquantel. Usually the Dr. Will give one 400 mg. Albendazole tablet. I was infested and this did not work. I had a huge learning experience and it took awhile to figure it all out. I have used everything. Ivermectin, garlic, neem oil, castor oil, dewormer for equine BUT SAFE FOR HUMANS. RAW LEMONS WITH SEEDS.PAPAYA with some skin , fruit and mostly seeds . Cloves. I’ve had the best luck with using a combination of different ones combined. Also health food store suggestions. I’ve been to two Dr.’s 2 hospitals, ear nose and throat, and urgent care . Delusional they say. I wish! Why Dr.’s have such a hang up about treating someone for worms or parasites I do not know. They must really like to diagnose delusions incorrectly. I had my vet test because All Ballad employees were saying it’s nothing when I would bring in samples. I’ve never seen anything like it. Abingdon, Va. And because I told them about the equine dewormer, I was taken to state mental hospital. Even after I explained it’s exactly the same as Reese’s pinworm meds bought otc. Pyrantel Pamoate. I only used dosage for my weight. Didn’t matter. I have been through hell. And still dealing with it. Wish you the best of luck.

Good morning Ian,

I am very glad to have found your site and this article. Great stuff – both the information and the responses to the comments. I’m hoping you can clarify a few quick things as I hope to treat my tank today.

I have a long running 38 g, heavily planted tank with CO2. Lots of substrate, wood and plants. Not many fish, but lots of mixed neo shrimp and 2 “Zebra” snails. I had some larger shrimp (Amano and long arm), but they were apparently killed by this outbreak on Planaria.

I have noticed these little worms now and then over the years my tank was running, but always just a few. I thought they were the harmless detrius, so I let them be. I went away for 4 days and my friend overfed. I came back and there were hundreds! I vacuumed up many as they slide up the glass, but still they come. I’m ready for the treatment and will go to the Pet Store as soon as they open.

My questions please:
– The stores don’t have Planara C, but other brands with 22.2% Fenbendezol. Is this the same?
-I have 2 Zebra Snails. Should they be removed?
– If snails are to be removed, can they live in a floating bag with some thing to hold onto for a few days (for heat purposes?

Thanks again Ian. Hoping for a quick reply. Thanks again Ian.

Hi Lonny,

As another commenter pointed out, the fenbendenzole concentration in Panacur c is 22.2%, so the others may be similar. However, the non-active ingredients may be a cause for concern. I have no experience with other medications and you would need to confirm that it is the same as Panacur C.

Are they zebra nerites? Panacur is harmful to nerites.

Why not take some of the tank water out, put it in a big bowl and put your nerites in that instead? This way you can feed them, monitor them as usual.

Thanks Ian,

I took the chance and used the product Safe-Guard. Had to! It got real bad. Watching them attack and kill pregnant shrimp is nasty.

Because the stores weren’t to open until the next day, I tried a diy trap. A small plastic water bottle with pin holes in the bottom, and then food and water inside. Capped and sat on the bottom. By the morning there had to be at least 100 in there.

Did the treatment last night and this morning I only saw a few. This evening I’m seeing a bunch again. Hoping the 2nd treatment tomorrow evening will do it. After that, I’ll look back through your article and the comments.

Thanks again.

PS – now I need to go look if you have an article and Q&A for BBA!

Hi Lonny,

That sounds like a horrible situation. I can see why you made the judgement call to use an alternative dewormer. I would love to hear about how or if safe-guard works. I used to recommend a product called planaria zero, it’s essentially just betal nut powder and works amazingly well for both planaria and hydra. However, due to it being difficult to locate (it’s a japanese product) and it not always being in stock, I updated to the recommending pancur c, which is effective too.

I do have an article on black beard algae, right here:

Thanks Ian,

Well, it’s 48 hrs since the first dose and I just did it again. I have seen more of them little buggers today. I sure hope round 2 kills them off. I have seen no words about a 3rd round.

Good news are all fish and even the shrimp babies look to doing just fine.

Thanks again. Now off to read your BBA article. You might be the most efficient killer I’ve dealt with 🙂

All the best!

It sounds like you have quite the infestation. If I was in your shoes, and the safeguard does appear to be working, killing them off, I’d keep dosing. But I’ll be surprised if the second dose doesn’t do the job – I have witnessed a 2x dose of panacur kill outbreaks where the numbers of planaria were likely in the thousands.

Just be mindful that if all of them die at once, and you don’t remove them, then it’s possible the rotting bodies could lead to an ammonia spike.

Hi! I’m currently dosing panacur to rid my tank of planaria. Are there any particular steps I should take regarding washing/disinfecting my siphons and buckets used to clean my fish tanks to avoid spreading planaria to other tanks? Should I be concerned about contamination via cleaning equipment?

Hi Gretchen,

If you run a multi-tank setup, then it’s typically recommended to buy a set of equipment for each tank to avoid diseases spreading. For instance, each tank would have it’s own net. Despite this, siphons are often shared among tanks. If you are dealing with an outbreak then I would disinfect any shared buckets, siphons and nets etc. If you use bleach or soap, make sure you rinse it thoroughly before leaving to dry.

Hi, this article was the most helpful that i’ve found. I just saw one worm in my tank but crawled out of sight as i went to get my net so I couldn’t look for these characteristics. When I see it again, if it is Planarian, do I keep my fish in the tank when treating it?

Hi Alayna,

It’s also possible it was a detritus worm which is totally harmless. But if it’s planaria, you would treat the entire tank with the fish inside.

I have a tank with an axolotl. I’ve noticed planaria worms. There were 3 at first and i use a cup to remove them. I spotted 3 more on my axolotls food and quickly removed them. No more. Spotted a thing dangling of the axolotls gills might not be it buuuut.
What should i do. I dont want to se a canine dewormer but if i have to ….

Hi Tom, unfortunately I do not have any experience with axolotls and could not confirm that canine dewormer will work the same as it does with fish.

Hi Ian I really appreciate you posting about this subject. Does your recommended treatment harm aquatic plants? My tank is full of plants.

Hi Cynthia,

Generally speaking plants should be perfectly fine. Canine dewormer does not affect them. However, if you have especially sensitive, high-maintenance plants, it might be worth researching how it affects that species specifically.

Ian will this work with a 20 gal with zebra danios, Red eye tetras, mollies, and fish of these sorts? I’m sure there planaria they move on the glass I find them at the top of the glass tank by the water line. I see white ones mostly but have seen some black ones slivering on the glass my water numbers are great and ammonia is great.. I’m grossed out how did they get in my tank had the tank 2 yrs now.

I’m also doing antibiotics in the tank i have a sick red eye tetra. Twitching and laying on its side struggling been that way for 8 days still hanging in there hoping it get better.

Hi Lisa,

Yes, this method is fish safe, myself and many others have used this in community tanks without any issues.

When you say “great” what are your exact measurements of Ammonia, nitrite, nitrate, pH and water temperature, how long each day do you leave the light on and how often do you do a water change?

I have used this treatment twice. Thought problem was cleared up but I now have lots of little white worms floating round the water. Too small to see if these have an arrow head. I am assuming that as I had a definite worm in there last week that first lot of treatment didn’t work. I have now repeated the treatment and waitin to do the 2nd dose. Worms still look wiggly and alive. Tank has cherry shrimp and 2 ghost shrimp. Planted 25L tank. Using the 500ml per 1g packet as no scales to measure. I am also very new to shrimp keeping. Need advice please ????

Hi Victoria,

Pull out your phone and take a photo and zoom in. You want to make sure you are using the correct treatment for what is actually in your tank.

They so small. Almost like tiny hairs. They not as big as the definitie planaria I managed to get a photo of last week. These are really tiny. Still moving on glass today. Haven’t seen the 2 large planarians I originally saw. Possible these could be diff ones. I have included a link to a video I managed to zoom into as phone was finding it difficult to zoom in as they so small. Hope it helps.

Hi Victoria,

Unfortunately, that video isn’t going to help, they could be rhabdocoela or any flatworm. You’ll have to use your best judgement here.

Hello Ian! First thank you for your blog, I’m less than a year into the hobby, and your blog is one of the few knowledgeable sources that helped me a lot.

I wish to ask you something, sorry this will be long, but maybe it will be useful to someone out there sharing my concern.

I am worried I have Planaria feeding on the detritus, and my ramshorn snails population was drastically reduced, however I did redecorate my plants and gotten rid of the bulkiness and favorable setting for snails to multiply, so I can’t tell if Planaria was the culprit.

I think I have Rhabdocoela in my nano tank, but I am still not sure yet. I like to tell myself they are not Planaria, because they are very small about 2mm and hiding in subtrate still. I saw them a couple of weeks ago. I do have however some detritus that appear only at water change but get eaten by the guppies, nothing alarming or signaling outbreak.

For now I cannot distinguish the 2 types of flatworms yet. I do know though that a couple of months ago I had Planaria (arrow head) I only saw 1 and it was big! I made a mistake of squishing it (with a sitck lol) because I had no clue what it was at that moment, and I panicked. After reading your blog and contacting my fish supplier, I used a dewormer and they were no longer visible. I had to repeat the procedure twice actually because I saw a tiny flatworm and I assumed it was Planaria again.

So fast forwarding till now, my nanotank has a batch of 15 endler guppy fry that are about 4 days old, and I do see the flatworms in the subtrate. I can see them on the perimeters of the tank inside the substrate. I can count about 3 or 5 if I am really focused on one side. They are visible on the side that is facing the wall (the side with most shade).

The mommy endler guppy didn’t make it unfortunately, and now I am left with baby fries with 2 ottocinclus, 1 endler male guppy, 4 ember tetra, and 1 cherry shrimp, and a couple of ramshorn. I don’t wish to move my fry because this tank is cycled since late summer and it is very stable.

So my question is since I can’t tell if it’s Planaria or not, should I be too concerned for now? Will they hurt my fry? I saw in your comments that dewormer might be too harsh for fry so I am going to skip it if for now, but I am worried my fry will be hurt.

If I wanted to gravel vac, how can I make sure my equipments are 100% clean and disinfected? I never gravel vac my nano tank, I do about a 50% water change every week, and change my filter cartridge every 4-6weeks. Honestly I never gravel vac-ed especially after learning there is something called planaria, detritus, and stuff like that, I hate to get some of them stuck in my cleaning tubes or thriving in my bathroom sink or toilet! Also we live in apartment, it would have been easier to dispose in garden.

Thank you in advance!

Hi Marie-Anne,

Thank you for the detailed write up. Planaria are most harmful to snails and inverts – things that live on the surfaces of your tank. If they are Rhabdocoela then they are absolutely harmless.

Gravel vaccing is highly recommended – this sucks out uneaten fish food and poop that detritus worms and other hitchhikers feed on. If you are going to share between tanks, you should wash the gravel vac.


for like a month we have planaria at our tank at work. there also live lots of shrimps and a turtle. because of the turtle, i dont know if i could use panacur. thats why i keep catching lots of planaria with a trap but i know they wont disappear completely this way. do you know anything about turtles with planaria?

at home i got a 25l nano cube. its very new, like 3 weeks old and one week ago i found little white worms. because of our planaria problem at work, i was shocked and went to get panacur directly. ive read on the internet i should put 1ml panacur on 1 liter tank water. then after 10 days, change 50% of the water and put panacur again for the 50% water.

i got one pill 250mg panacur at the vet. you only get this at the vet here in germany and some vets wont even give it to you. ive put the 250mg pill into 250ml water already for easier measuring and now i dont have any left for the second time. everyone says you need to do everything again after 10 days because of the new eggs that hatch. but now my tank is pretty new and i dont think the planaria would have been able to lay any eggs already. do i still need to redo everything?

today, a week after putting panacur, i took a closer look at the worms and now im not even sure if its planaria. ive read that planaria without that triangular head do exist. i hope its ok to post a link to a picture here.

there is soil in the tank and everywhere they say soil “sucks” the medication in and it takes longer for it to work and get rid of it. i didnt even get to put any animals beside some little snails that survive panacur in. do you know how long it would take to get the medication out of the tank again so the snail i would like to put in wont die? does it really take months or are there any ways to clean everything faster?

Hi Ren,

Unfortuantely, I have no experience with turtles and would not be comfortable giving advice here. The good news here is that those look like they are Rhabdocoela, which are considered harmless yet may explode in numbers if they have the appropriate food source also, certain breeds appear to be immune to fenbendazole. Activated carbon and a few water changes will see the tank become snail safe in no time.

Hi Andrew,

Good question. Panacur is considered plant safe. However, if you stock particularly sensitive plants you may want to do further research.

Thank you for the Advice on planarian. Do you have a recommendation on how to decontaminate snails before adding them back into a tank? I keep about 12 different varieties of snails including multiple types of Tylomelania. White Planarian are reeking havoc on them and my bivalves. I will need to remove 40 or so snails and bivalves from the Aquarium to treat with dewormer. My concern is planarian hiding out on the removed snails and bivalves, thus reinfecting the aquarium upon return. Any ideas?

Hi BB,

Good question, short of putting them in a quarantine tank and monitoring really closely (then shifting them to *another* quarentine tank and repeat, I don’t really have a good solution with this.

Thank you for the valuable information! I’m asking if this will kill planaria eggs in a few days also? Or is there another treatment that needs to be done later for this, besides the two treatments a couple days apart.

Hi Connie,

Good question, my experience and from the other comments left here, the two treatments are typically enough.

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