Planaria in aquarium three ways to kill flatworms and prevention tipsPlanaria in aquarium settings aren’t uncommon, but that doesn’t mean they can’t become your worst nightmare. As predatory pests, white planaria can hunt down ill or juvenile fish, and they absolutely love feeding on shrimps and snails.

If you’re looking to safeguard your community aquarium from a full-blown infestation, you’re in the right place. This planaria-eliminating guide will walk you through all the fastest solutions to getting rid of the pests. Additionally, we’ve also covered helpful topics like prevention tips and a DIY trap in case you don’t want to splurge on that extra cash!

What Are Planaria in Aquarium Settings?

Planaria are a type of flatworms belonging to the Turbellaria class. They’re found in various regions worldwide in salt and fresh water bodies. The latter is the reason why these worms are common in fish tanks and, in large numbers, can be a danger for the inhabitants.

What Causes Planaria?

Planaria don’t tend to last very long in freshwater aquariums, especially if the tank’s fish-only and includes stellar predators like Angelfish. However, if you’re the proud owner of a community aquarium with snails, shrimps, and the like, flatworms can be a giant problem.

As to what causes these underwater pests, the answer is, avoiding them is pretty tricky, considering they’re present in most types of water. They’re also excellent stowaways and can book seats on all types of objects, including rocks, fish, plants, etc.

In short, most people will have a flatworm or two in their tank, brought over by a recent addition. That’s why we always recommend using isolation tanks.

– Additional Information

Once a single wormy has made its way into your aquarium, it can feed on all types of stuff. Flatworms can feast on fish poop (disturbing and helpful at the same time), food particles, biofilm; you name it.

What makes things worse and that these flatworms reproduce via asexual reproduction. In theory, at least one worm is all that is required for a tankful of flatworms. Thankfully, practical life is a little more reasonable.

Generally, flatworms require sustenance and unhygienic water conditions to thrive. That means the single worm that found its way to your tank wasn’t your fault. Whereas when Planaria are swimming in every corner of your tank, that’s the result of poor tank conditions, in short, this is the reason why the flatworms grow in numbers.

Planaria also have the unhelpful tendency to pop up in tanks where there’s overfeeding. A different perspective would be that Planaria are the kind of unwanted guests that need no invitation. Still, once they’re in your house, the slightest encouragement will lead to these flatworms ultimately going out of control.

How To Get Rid of It

A white flatworm or two in your fish tank isn’t too worrying. But seeing the pests increase in numbers until they’re filling up the aquarium is something you want to avoid damage to the tank inhabitants.

Thankfully, there are several ways you can kill planaria in aquariums with a minimum of fuss. This section will list out all the methods you can utilize to clear out these pests from your tank, hence if you’re dealing with an infestation, you might want to pay attention here.

– Chemical Treatments

Fish keepers are a little iffy about using chemical treatments in aquariums and with good reason.

First off, it’s tricky to predict how the ingredients put in the treatment can affect the tank’s ecosystem and its inhabitants. Secondly, it takes a bit of time for chemical treatments to clear out from the water.

The good news is Planaria treatments(s) come in quite a few variations. For example, some aquarists have reported massive success killing planaria worms in fish tank settings with dewormers such as Flubenol and Panacur. However, the downside to these treatments is they’re less than ideal for tanks with snails.

The active ingredients used in the dewormer medications can harm snails and interfere with the species’ repopulation. That means if you have a community tank with any type of snail, using dewormer medication to treat Planaria isn’t an option for you.

Before you get too disheartened, however, you’ll be happy to know that there are aquarium-safe worm disinfectants available on the market. These disinfectants feature natural ingredients like betel nut palm extract that are safe for all fish tank inhabitants.

Product Features:

Besides that, the products feature clear instructions on the amount of disinfectant to use. That means you won’t have to make guesstimates and wonder if you’re doing the right thing, like with dewormers. Some products even feature after-care instructions so that aquarists are in no doubt about how to clear the water of any remaining traces of the chemicals.

On the whole, aquarium-friendly worm disinfectants can clear your tank of Planaria in 72 hours, and it requires fish keepers to remove carbon filters before use. If you notice the product mentions ‘safe for freshwater fish only,’ it’s best to remove your snails and shrimps from the tank.

Moreover, be advised that dead Planaria in the aquarium may lead to ammonia levels spiking. That’s why it’s best to have your siphon or vacuum ready to suck up all the worm debris.

Another protip for Planaria treatments is increasing aeration and keeping the aquarium well-ventilated to help get rid of the chemicals faster. You’ll also need to use carbon and conduct a water change (as per instructions) to make the fish tank water safe for all the animals in it.

– Planaria Traps

If you’re dealing with Planaria in fish tank settings in manageable numbers and don’t want to deal with the hassle of chemicals or clean up worm bodies, you can set up a Planaria trap instead.

These traps are readily available in aquariums or online retail sites. These traps are generally tube-shaped with one or more openings to allow the worms to wiggle inside and be trapped.

Setting up planaria traps is almost effortless too. All you need to do is place some bait inside (shrimp works like a charm) and place the tube in the water. The trap will take some time to build traction because it lures the worms using the bait.

Key Points for Trapping:

However, leaving the trap in the water overnight is likely to result in a worm-free fish tank by morning. Once the worms are trapped, all you need to do is fish out the worms and drop them in boiling water to kill them.

The slight disadvantage to Planaria traps is that you’ll likely need to repeat the process (of trapping worms) two to three times to clear the tank or bring their levels down.

When buying these traps, it’s best to opt for a design with three holes to gain maximum effect. The fewer the number of holes, the longer it’ll take to catch the Planaria floating around.

Fish keepers should avoid feeding the fish once they’ve set up a trap because this can lead the worms away from the trap towards the fish food. It’s also best to keep the lights dim or switch them off because the flatworms prefer darkness and tend to be more active in it.

– Worm-eating Fish

Fish that eat Planaria can offer fish keepers another unproblematic way of ridding their tanks of the flatworms. However, the method has its set of pros and cons. For example, using fish to rid the tank of worms doesn’t make use of chemicals, so there’s nothing to upset the aquarium’s ecosystem. Then there’s the fact that you don’t have to fish out dead worms and the worms make a healthy snack for the Planaria-hunting fish.

The disadvantage of using fish to kill off Planaria is that most worm-eating species are carnivores. That means they’re also inclined to eat tank mates like shrimp (if you have any). Hence, it’s a balancing exercise, and not everyone can afford to adopt this measure. Fish species renowned Planaria-lovers include Guppies, Gouramis, Goldfish, Angelfish, Mollies, etc. 

How To Make a DIY Planaria Trap

If you’re not inclined to spend cash getting a readymade Planaria Trap with all sorts of added costs, you can easily make one at home, with minimal cost. Plus, DIY Planaria traps are straightforward to make and will work like the commercial ones if you know what to do. All you need to do is scroll below to discover how it’s done.

By using a small-sized PET disposable water bottle, 7-gauge needle and Fish food or shrimp meat (for bait), you’ll have your DIY trap ready in no time.

Thoroughly wash the PET water bottle with dishwashing soap. Dry the bottle and set it aside. Grab the 7-gauge needle, turn the bottle over and punch four holes (on each dent) at the base. Twist the bottle’s cap open and drop in your bait of choice. Fish keepers can use fish flakes and pellets for the task too. Place the lid back on and ensure the cap’s fit is snug.

Dunk the plastic bottle (base first) into the aquarium and allow the bottle to fill up with water. Doing so will let the bottle stand upright, without any water bubbles causing swaying or instability. Once the bottle is full to the brim with water, set it down on the fish tank’s base. Dim or switch off the lighting to tempt the flatworms to become active.

Tips and Tricks To Prevent it

Planaria in aquariumYour job as an aquarist is not so much avoiding the presence of Planaria as it is controlling it. You can certainly cut back on Planaria’s presence by setting up a quarantine tank for all your new tank additions.

However, if you don’t have the time or the space to set up an extra tank, that’s okay. This section will list some easy-to-implement tips and tricks to help keep your aquarium flatworm-free.

Here’s what you’ll need to keep in mind:

  • A Planaria population can explode in fish tanks because of inadequate hygiene maintenance. Consequently, the best way to keep a check on flatworm numbers is to work on improving your cleaning game.
  • Regular water changes are a must in fish tanks. They help dilute toxic compounds like ammonia and eliminate other pollutants building up in the water. A 10 to 15 percent weekly water change can go a long way in stopping the buildup of fish waste, plant debris, and other substances that attract Flatworms.
  • Sometimes beginner aquarists can overlook cleaning the gravel substrate as they conduct water changes. But, a water change won’t do much if your gravel contains gunk pockets that are a breeding ground for all sorts of nasties. Make siphoning (vacuuming) the gravel a part of your cleaning routine by tackling a few areas at one time.


We’re hoping our fellow fishkeepers are content with all the data they’ve gathered here about how to combat Planaria in aquarium arrangements of all kinds. The task of controlling these water pests isn’t too complex and requires the following:

  • Utilizing an aquarium-friendly worm disinfectant with natural ingredients like betel nut palm extract. These disinfectants also come equipped with clear instructions and before and after-care guidelines.
  • Fish keepers with a moderate number of Planaria can utilize Planaria traps. These traps usually have a test-tube shape with three or more openings designed to lure the worms in the container and trap them.
  • Another trip to eliminate flatworms is to stock up your tank with Planaria-loving fish like Mollies or Angelfish. But, if your tank contains shrimps (or snails), be sure not to mix them with carnivorous fish in case they become prey.
  • Hobbyists looking to save some cash for dealing with a minimal number of Planaria can create their own DIY trap using a PET plastic bottle, a 7-gauge syringe, and any type of fish food (live food or commercial pellets/flakes).
  • Planaria are tricky to keep out of an aquarium, but generally, their numbers can climb due to a poor cleaning routine. Regular water changes and vacuuming the gravel is essential to control substances that the Planaria feast on.

Planaria might be a scary sight, but they can be dealt with without too much difficulty if you know what you’re doing. Our advice is to play it safe and keep flatworm numbers down by cleaning your tank regularly.

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