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FAQs on Freshwater Worms of All Sorts 2

Related Articles:  Invertebrates for Freshwater Aquariums by Neale Monks, Choose Your Weapon: Freshwater Fish Disease Treatment Options by Neale Monks,

Related FAQs:  Freshwater Worms 1 Planaria, FW Worm Identification, FW Worm Behavior, FW Worm Compatibility/Control, FW Worm Selection, FW Worm Systems, FW Worm Feeding, FW Worm Disease, FW Worm Reproduction & FAQs on: Worm Caused Diseases,  Platyhelminths/Flatworms: ( Flukes, Planaria, Tapeworms and Leeches), Acanthocephalans, Nematodes/Roundworms (e.g. Camallanus),... Anchor "Worms": See FW Crustacean Parasitic Disease, & Worms as Foods, FW Invert.s 1, Aquatic Insects, Crustaceans ShrimpsTerrestrial Hermit Crabs,

Need help to identify a worm    4/20/20
I found a worm outside of my house, just near to my dog, when I accidentally step on it. After looking it I found this so weird because it is first time i have ever see worm with glowing blood. I have attached pic of it, with flashlight and without flashlight. Is it baby millipedes? So confused.
<Hello. That's quite the find! It appears to be a polychaete rather than a centipede or millipede. I say that because the body appears to be soft, with no obvious exoskeleton, unlike those two arthropod groups. A polychaete ('bristleworm') seems more probable than an oligochaete ('earthworm') because of the fleshy appendages on each segment. However, terrestrial polychaete are very rare, unlike oligochaetes, which include numerous terrestrial species. So my guess in the absence of any other information would be that this is a marine polychaete, perhaps dropped by a bird onto dry land somewhere near your home. Of course if you live near the sea, this makes sense -- but if you're more than a few miles inland, that would be an unlikely explanation. There are freshwater polychaetes, but they're mostly quite small and unobtrusive, and not at all common.
Fluoresce in polychaetes is quite well documented, though again, to the best of my knowledge only among marine species. Better photos of the head end of the animal would help -- polychaetes usually have obvious jaws complete with sharp pincers in many cases, as well as eyes and tentacles, all of which are absent from most oligochaetes. It would also help to know where you live. In the Southern Hemisphere, velvet worms might also be considered, but you wouldn't find these in Europe or North America, and again, they only live in specific habitats such as rain forests. Cheers, Neale.>

Long thin worm like creature hanging from outlet of gravity filter
Hope you can help. Over the last several days I have noticed a thin (maybe 0.5mm in dia) white strand of something hanging down from the outlet of my built in gravity filter on my Aqua One UFO 550 tank.
<How odd.>
Today, I noticed it had grown in length substantially and when I tried to grab it with some tweezers, it suddenly and quickly retracted back into the filter outlet, so whatever it is, it’s ALIVE! I estimate it to be between 100mm and 120mm long and think it is some kind of worm, maybe feeding in the water current and living in the part of the filter that contains the ceramic biomedia.
<Sounds like it! But really would need a picture to be sure.>
The Tank has 7 Angelfish and 3 Bristle Nosed Catfish and 6 Golden Apple Snails and all seem healthy. Water quality is well maintained, pH 6.8, Ammonia 0.25ppm, Nitrate 20ppm and Nitrite 0ppm and I do a regular (3 to 4 week) water change of ~30 litres and always add Prime.
<Apart from the ammonia, all seems fine. Zero ammonia is always the aim, and whole at pH 6.8 you'll have less toxic ammonium rather than free ammonia, do think about whether stocking, feeding, and filtering are adequate. Do also check the ammonia level of your tap water.>
Any idea what it may be and is it dangerous to the livestock?
<Unlikely. There are various free-living nematodes and especially oligochaetes (such as California Blackworms) that can get into fish tanks. They don't really do any harm, and can actually do some good in 'deep sand bed' settings. With that said, in excessive numbers they can indicate too much organic material (i.e., food) in the tank, which shines a light on maintenance and stocking.>
If so what’s the best way to get rid of it.
<Well, the obvious is to open up the filter and take a look! If it's a free-living nematode or oligochaete, you can either remove or leave it in there, depending on your point of view. I set up little critter tanks around the house (basically large jars on windowsills) to observe anything like this I find in my pond or my daughter's Triops tank. It's a fun addition to the hobby.>
<Cheers, Neale.>

Worms in freshwater substrate   4/23/18
I found several of these worms buried in the substrate of my 46gal bowfront, today. Any idea what they are, if I should get rid of them and if so, how? They’re about 1mm thick, and maybe 1.5 - 2” long at a guess? They were pretty upset to be disturbed and all balled up. There are two balled together in this video.
<No video attached. But as a general rule, freshwater worms are harmless. Beneficial, even. Do look up freshwater Oligochaetes for examples of the 'good' kind of worm. California Blackworms are quite common and used in freshwater deep sand beds. Tubifex less positive in the sense of preferring/indicating relatively dank conditions, but in themselves harmless, even enjoyed as food by most fish. Cheers, Neale.>

shallow dug well. Worms?     8/7/17
I’m seeing whitish worms like angel-hair spaghetti in my dug well decades old. Might these be dangerous parasites (nematodes) or some such?
<Mmm; not likely dangerous, BUT I would have a water quality outfit check them out>
Some approach 7 or 8 inched in length.
I am no longer drinking this water. But have for decades.
thanks for any info,
<Most worms are not harmful to humans; including the vast majority of Nematodes. Bob Fenner>

What the heck is this?!     2/13/17
I walked in to find this crazy white worm lookin back at me. It is probably about 2 inches long and my Beta is scared half to death of it. What is it and is it dangerous? I keep up with the tank cleanliness and don't over feed my fish. What else could I do to prevent this from happening again?
<It's an earthworm or something similar (i.e., an oligochaete). Probably unhappy being underwater, though there are one or two truly aquatic species that sometimes appear in batches of live food. If it's an earthworm, could you could kindly return it to the nearest compost heap or clean patch of soil, that'd be great. Earthworms are fantastic animals. There's a great book about them -- "The Earth Moved: On the Remarkable Achievements of Earthworms" -- that I'd recommend to anyone. Aquatic Oligochaetes should be returned to streams or shallow ponds. Compare and contrast your creature to photos of the Oligochaetes native to your particular country and act accordingly. Cheers, Neale.>

Worms in planted tank.      11/21/16
Hello everyone.
I have written before about my Hillstream loaches, which I still have and are still breeding. Thank you again for your help with my loaches. I also have a 60 litre planted tank, 24 " long, 12" wide, 12" deep that has been set up for 3 months now. Ph 7, ammonia 0, nitrite 0, nitrate 5. External filter rated at 800 litres an hour. It's a planted tank with jbl Manado
substrate. There are 7 Boraras brigittae, 3 Otocinclus catfish and red cherry shrimp. I also have these worms in the substrate which hopefully are not harmful to my livestock.
<Probably not, but they're huge! Never seen anything like them. They look like they're round in section, which rules out planarians. Their size seems much too big to be free-living nematodes, and they seem to lack obvious bristles, which rules of Polychaetes. That leaves two options, Oligochaetes and leeches. Leeches sound alarming, but many species are predators, not parasites, feeding primarily on small crustaceans and insect larvae. Common enough in ponds, these free-living leeches have a flattened body and swim, rather than burrow. Furthermore, their swimming is distinctive, undulating,
almost like a snake. On top of that, they have obvious suckers at each end, so can't really be mistaken for anything else. Oligochaetes are earthworms and their kin: if these worms have an earthworm-y appearance and behaviour, they're probably Oligochaetes, virtually all of which are harmless detritivores. Lumbriculus spp. are among the best known, for example the California Blackworms sometimes kept in aquaria as part of a freshwater deep sand bed; while Tubifex spp. are familiar to aquarists (especially older ones!) as a cheap but sometimes dirty live food.>
A photo is attached. Hopefully the photo this time isn't too big. Any help in identifying these worms are much appreciated. Carol.
<Hope this helps, Neale.>

Re Worms in planted tank.     11/22/16
Carol; would you pls re-size and re-send your email? Just a couple hundred Kbytes... not twenty megs. Am in Africa and there's no way I can dnld. such files. B
Video from Carol Lucas     11/22/16

Thank you for your response. This is the smallest I could get the video at the moment. The quality isn't great. Hopefully it will work. Thank you.
<Who is this for? I can only download a few percent of this in an hour. Bye. B>
re: Video from Carol Lucas     11/22/16

Sorry. I spoke to Neale yesterday.
<Ah; thank you. Could you post your video to YouTube or such and (just) send along a/the link? BobF>
Re: Blackwater for Featherfin catfish?
Am out in Madagascar... can only download files of a couple hundred Kbytes.
Not yours of 16.5 Megs. Deleted. Re-size and re-send. B

Worms in my tank!   5/29/16
Hi, I have found a heap of tiny thread like worms in my freshwater tanks.
They seem to be float/swimming around in the water but haven't seen any on the glass. In the water they look white but when I get them out of the water they turn pink/red. I'm worried they are detrimental to my fish and/or tanks.
<They are not.>
I've searched your other worm related articles but ant seem to find a description that fits. I have attached some photos below. If you are able to help me understand what they are and the dangers of them in my tank I would be very appreciative!
<No danger at all. But do indicate surplus organic matter for them to feed on, whether directly or via the microbes acting as decomposers.>
The tanks they are found in house Bristlenose catfish, and various other L number catfish so the tanks can get quite messy between cleans (each weekend). Thanks in advance for any and all advice!
<Answered your question right there. I'd ignore them, but I'd also keep a better grip on tank cleanliness, so that over time the populations of worms declined. Too much organic matter in the tank means your filter is having to work harder than it should, and nitrate levels are going to end up a bit higher than they would otherwise. Cheers, Neale.>

Re: Worms in my tank!   5/29/16
Thank you VERY much Neal! I was starting to panic.
The tanks that house the catfish are my two bottom racks so gravel vaccing is always difficult using traditional gravity fed vacs but I do use the Eheim quick vac pro that is battery operated
<Never found these much use, to be honest.>
and 50% water change each Saturday.
<Much more useful.>
I may need to look at how my tanks are set up and remove the messier cats to a higher tank to make gravel cleaning more effective. As long as I know they are not something harmful I can deal with this. Thank you very much!
<Welcome. Neale.>

Planaria or similar in freshwater tank       8/29/15
Hello, I am writing due to an issue I am having in my freshwater tanks. I have several, including one community, one invertebrate, one snail only and one Corydoras only. The issue with the worms began in my invertebrate tank.
Honestly, this freshwater home is what I call a "mercy tank". I started it to save the uninvited guests that I would often find in newly purchased plants, driftwood, etc.
<It sounds a really neat idea.>
This small tank now inhabits few species of dwarf shrimp, "pest" snails and most recently Planaria.
<Planarians are safe and common inhabitants of fish-free aquaria.>
I assume these problematic worms to be Planaria based on what I have read in prior posts on your site. They are tiny, skinny, white worms that seem to do no harm to those around them.
<Correct. They're fascinating animals under a microscope too, with all sorts of weird biological quirks to read up on.>
Plus I have to admit I often neglect the mercy tank since it isn't something I enjoy having.
<Benign neglect isn't a bad thing.>
Regardless, it is not filthy at all..and because of the dwarf (grass) shrimp I take better care of it than I normally would. After spotting the small worms, I began to clean the mercy tank more frequently. I have seen an improvement.
<Correct. Planarians like these will be feeding on organic detritus, and the more you clean the tank, the less food for them.>
Now, to the problem! I always rinse my tools in hit tap water before switching tanks, but today I suddenly saw a few of these white worms in my snail tank. This tank is not neglected or overfed. I am confident that the worms were transferred due to lack of proper sterilization of my equipment.
Am I possibly correct?
<Likely so, but could just as easily got there via aquarium plants or the snails themselves. Most aquaria (probably all) have at least some planarians in them, but being very small and often nocturnal we rarely see them.>
I have read about fluke tabs on your site. Are these safe for snails?
<Almost certainly not. It's a pretty obsolete medication that's not widely recommended anymore. Lots of horror stories on the Internet if you can to peruse. GeoChem "No Planaria" is a much better alternative.>
I would like to end this issue before it spreads to the tanks in which my fish inhabit. Plus, I am grossed out!
<Dipping shared equipment in aquarium steriliser will prevent cross-contamination, but bear in mind numerous fish will eat flatworms when hungry, so it's pretty rare for them to become a problem in FW aquaria unless that tank is seriously neglected/dirty.>
Please help.
Thank you,
<Cheers, Neale.>
Want to add toy original email: paranoia or something similar       8/29/15

I just noticed that my snails seem to be bothered by something I can't see.
Two of my Malaysian trumpet snails were climbing the glass to the surface, then appeared to be shaking.
<MTS will rise to the top of the tank to get to the oxygenated water if the tank conditions aren't good. If you see them climbing the glass during the day, as if abandoning the gravel, that can be a bad sign (at night its normal for them to climb on the glass).>
I have a mystery snail as well that looks as if it is biting or scratching it's body directly under it's shell. They all look irritated.
<Possibly so. Check water quality and pH.>
Is this a vicious species of Planaria or am I dealing with something much worse??????!!!!
<There is indeed a predatory flatworm called Procotyla that will attack small prey, even baby shrimps (though not fish). Cheers, Neale.>

weird tiny pink worms?       6/23/14
Dear WWM crew,
I do not have an aquarium, but hope you can help with a weird water-related problem. I have an old cat that sometimes drinks from a running water fountain with a charcoal filter. The filter is very basic, just a small plastic cartridge with charcoal pellets, and there is a piece of fuzzy white fabric that keeps the pellets from dropping out of the cartridge.
Generally, I only clean the hard plastic portions of this fountain, but today decided to take apart the filter. There were some pinkish orange bits that looked like mold embedded in the fuzzy fabric. I took everything
apart, tried to rinse the pinkish bits out of the fabric, cleaned what I could, and let it all dry next to my sink.
<Mmm; I would bleach all the unit but the carbon... likely the carbon has removed enough of the sanitizer (chlorine based) that some "critters" have been allowed to become situated...>
Hours later, I was disgusted to discover a number of tiny pinkish worms moving vigorously around that side of my sink. They were slim as human hairs, and the largest were about 5 or 6 mm long. It was not mold in the fabric - it was worms.
<Likely Nematodes of some sort, species... there are MANY>
They do not look like mosquito larvae. Any ideas what this might be? I just want to know whether these might be parasitic to me or the cat, or dangerous to either of us.
<Highly unlikely to be dangerous; parasitic>
I'm afraid I haven't changed the water as often as I could have, given that there was a filter.
I've disinfected with bleach around the sink and anywhere the bowl has been - which knocked these things out - but it is a bit unnerving. I do not see them in any standing water bowls. I'm hoping this is no shrinking link between pest and pets.
Gratefully yours,
Jenny B.
<Not to worry. Folks ingest this phylum of worms daily... Very common; take a look... on wiki perhaps. Bob Fenner>
Re: weird tiny pink worms?       6/23/14

Wow, what a fast response! Thanks!
<Certainly welcome. BobF>

strange worms in my guppy tank   11/13/10
Ok I have these tiny little white worms in my male guppy tank but let me give you some background. I recently bought some very pretty fancy males and introduced them into my 60 gallon tank. After a bit of a go at my females I placed them into my 5 gallon "male" tank with my other males.
<Too small a volume for these fish>
Within a month some of my females along with some platys in my tank began to swell and look like a pinecone and die. I looked it up and dropsy was what I found.
<A descriptive term, summat like "colds" in humans... Of various etiologies... causes>
Right after dealing with that and dealing with my last case of dropsy I noticed one male in my small tank mysteriously died. It was one of the pretty new males. I assumed it was killed by the other males and dipped him out and thought nothing of it until a couple days later I noticed a tiny cone shaped snail in my male tank. Within two weeks of that my male tank had many snails. Just today I looked in my male tank that I had not looked closely at for a couple days and was shocked to find thousands if not hundreds of thousands of very tiny little white worms that you have to look hard at to even notice. I also noticed a dead male in the bottom of my tank. Since then my males have acted strange. Just sitting there, not very
interested in eating when they are usually ravenous. I grabbed an eye loupe 10x magnification and looked closer at the worms and they were so tiny I had to grab another and stick them together and then I could see that the worms appeared segmented, grayish splotchy white, and have flat heads. The swim through the water like snakes and inch along the glass like caterpillars. They also seem to distress the snails greatly, they will stick onto the snail and the snail will shake its shell violently
until the worms are detached. A month before this I had white apple snails that ALL died mysteriously. I have battled these little buggers before and the only way I defeated them was to take out my fish completely break down my tank and pour boiling water over my gravel and let it sit and dry in the sun for a couple of days. I never saw them again until just now with the strange appearance of snails and they are only in the male tank that has the snails they seem to be contained there. I don't know if they have anything to do with the dropsy
<Doubtful... but the dead, dying fish likely provide/d food for the worms>
I figured I would mention it just in case. I tried to take a photo but the worms are so tiny they would not photograph at all. So far three dead males that died without any physical deformities and six dead females claimed by dropsy most of which are guppies. I currently have 4 tanks: my large tank, my male tank, a Betta tank with a single Betta, and a fry tank. I now fear for my tiny fry for a snail just showed up in their tank as well as my Betta tank, all of the small tanks are side by side. Please tell me what these aggressive worms may be, how to get rid of them, and what danger they pose to my fish. Also please note I have treated my tank with malachite green and it did nothing.
<Not useful here>
Under the advice of a very prolific fish breeder I loaded my tank down with aquarium salt which did no harm to the fish but also none to the worms. I have vacuumed the gravel just to have to worms return to great numbers within a week, I have tried parasite clear when I had the first case years ago and it didn't help but I am not entirely sure these worms are the same.
Please help.
<The worms can be easily killed... Read here:
and here re Guppy disease:

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