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FAQs on Freshwater Worms of All Sorts, Identification 2  

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

Related FAQs: FW Worm Identification 1, FW Worm ID 3, FW Worm ID 4, FW Worm ID 5, Freshwater Worms 1, Freshwater Worms 2, Planaria, 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, Worms as Foods, FW Invert.s 1, Aquatic Insects, Crustaceans, Shrimps, Terrestrial Hermit Crabs,

Wormlike wigglers in cycling tank      /Neale        2/19/15
Can you guys identify what these are? They appear to be little white worms in the water but zoomed in they look like larvae of some type. This is in a new setup about 4 weeks old, no fish, fresh black onyx sand, RO water, and 81 degree temp. They seem to have come out of no where. Thanks in advance. Video below image.
<Midge larvae or something similar. Totally harmless, and likely fish food if you add anything insectivorous of appropriate size (such as tetras). Not mosquitoes, anyway, which attach to the surface film of water. Cheers, Neale.>
Wormlike wigglers in cycling tank    /RMF
Can you guys identify what these are?
<Mmm; yes>
They appear to be little white worms in the water but zoomed in they look like larvae of some type. This is in a new setup about 4 weeks old, no fish, fresh black onyx sand, RO water, and 81 degree temp. They seem to have come out of no where. Thanks in advance. Video below image.
<Insect larvae... heads appear too small to be mosquitoes, maybe Midge larvae. I'd net out, remove. Bob Fenner>

Re: Wormlike wigglers in cycling tank      2/19/15
Thanks for the reply. I added what is now a very full and satisfied Platy to the tank.
<Heeee! I bet!>
The thing couldn't get to the little morsels fast enough. Happy to say that all wigglers are gone.
Thanks again.
<Cheers Mark. BobF>

Worm    1/20/15
I am not sure if you can help me or not, but, I found a strange long worm in my pool. It appears to possibly be some kind of parasite. Would you be able to identify it if I sent you a picture?
Thank you,
<Likely can help you narrow the ID down. Doubtful that this is a parasitic species. Bob Fenner>
Re: Worm

Here are some photos. I tried to send a video but I couldn't get it to attach.
<Oh yeah... a horse hair worm, Nematomorpha/n... not to worry. BobF>

Re: Worm    1/20/15
Ok. Thank you. That's what I thought, but wanted a second opinion.
<Cheers, B>

Strange worm in aquarium!!     1/10/15
Hello crew! It's been a few years since I've needed help from you guys. My
system isn't in need of help but I am hoping for an ID on a strange worm.
So I was cleaning out an aquarium that has been set up for four months. I
am converting it to a Betta paludarium. Really just an emergent/submerged plant set-up with soil(Walstad). Anyway, while I was cleaning this tank out I found about six of these worms crawling around under the substrate.
substrate is natural creek sand that I rinsed and baked a few months ago(four as I stated before!!). Anyway. After Initial l set-up I didn't change anything except to move fish in and out of this system. I never fed this type of worm. Just frozen daphnia/flake/Spirulina flakes. I used local aquatic plants
<Ah yes; likely the source>

for this system so I'm sure that the eggs of these guys
somehow hitch-hiked in on the roots of some plants or, something?! Anyway, Can you guys help me with an ID and how do you think they survived for so many months?
<Yes; some sort of Oligochaete ("few bristles") segmented worm... same group as earthworms, Tubifex, Blackworms. Not harmful. Thanks for sharing.
Bob Fenner>
http://s26.photobucket.com/user/HDBenson/media/Mobile%20Uploads/IMG_20150108_075953_hdr_zps7yevwwba.jpg.html] [IMG]http://i26.photobucket.com/albums/c120

/HDBenson/Mobile%20Uploads/IMG_20150108_075953_hdr_zps7yevwwba.jpg[/IMG] [/URL]

Tiny worm(s)     12/25/14
I checked the site and didn't see this little guy. It is living on a fake plant in a ten gallon freshwater aquarium. Video attached. Happy to have it if it isn't harmful but would love to have an ID. Thanks for any help.
<Some bit of fecal material. Bob Fenner>
Katie Dunahoo
<Link to "Poop of Earl" (sans soundtrack) >

little worm <not> in freshwater tank      7/18/14
Good evening! I would like to ask your help identifying a worm i found yesterday. While cleaning out my tank, i noticed some little, very light colored worms on my Anubias nana. I put them in a bowl for observation. They didn't climb on the wall, just wiggled on the bottom. I haven't seen them in my tank before, though they are small and my gravel is light so i might have missed them. There were only a few. The body is round, so i think it's not a flat worm, there was also some black coloration on the head. I inspected the leaves and i found some brown round things on one of the leaves, maybe the eggs or something? I took some pics with my phone but they aren't the best, i don't have a camera so i can't really make better ones, sorry. My questions are what is it, is it harmful to my fish, do i need any treatment for the tank? My friend suggested that i throw away my plants, but i don't really want to if it's not necessary. I live in Europe.
<Likely these are aquatic insect larvae, possibly imported on the plants, and in any event, almost certainly harmless. Nematodes (roundworms) tend to be uniformly coloured (usually white) whereas insect larvae (such as "maggots") have distinctive head regions that are darker than the body thanks to their eyes and jaws. Hope this helps, Neale.>


Re: little worm in freshwater tank 7/20/2014
Thank you for your reply, I'm relieved. Than i go and replant my tank :)
<Most welcome, Neale.>

reddish leech looking creatures in my yard      7/10/14
in the last week we have found 2, 2inch dark reddish, skinny leech looking things in my back yard. we don't have grass in my yard. its dirt. someone told me that its a parasite! never seen these before and im worried. have children and pets. please help! thank you, sherie
<Without photographs can't really be sure. Would also need to know what country you're in, and what your local climate is like, because that makes a huge difference to the sorts of animals where you live. You're not at all clear where you found these parasites; we're "experts" on ponds perhaps, but not lawns, patios, or other sorts of garden features. But as a rule of thumb, if the "something" is big enough to see easily and just lying around in an obvious way, it's not a parasite. Parasites are mostly tiny (even microscopic) because they need to get inside their hosts, or else secretive, like bedbugs and leeches, because they need to creep up on their hosts. The organisms you've seen sound much more like earthworms, freshwater leeches, or possibly some sort of large insect larva (such as Leatherjacket larvae). There are of course parasites that affect dogs and cats, notoriously Lungworm here in the UK at the moment, but the parasites themselves are essentially microscopic and transmitted via snails and slugs
(which are in turn infected by faeces from an infected dog). You should get yourself aware of the local parasites that pose a risk to your pets by consulting your vet; they usually have leaflets in their offices (detailing risks and symptoms) as well as suggestions on appropriate preventatives and treatments. With regard to children, we're obviously not medical doctors so refrain from giving you advice here; if you are concerned, photograph the suspected parasite, show it to your general practitioner and act accordingly. Cheers, Neale (who's merely a doctor of rocks!).>
Re: reddish leech looking creatures in my yard

Thank you for your reply. If I see another one I will take a picture and send it to you. And I live in Laplace Louisiana
<Glad to help. Neale.>

water worm      6/29/14
can you identify this worm and let me know if it is dangerous? I found it in my swimming pool
<It's an errant Polychaete of some sort, and no, not dangerous. Any idea where it came from? If the pool is outdoors and near the sea, that's presumably where it came from, possibly dropped by a passing seabird.
Cheers, Neale.><<Well-done Neale. RMF>>

Worms of some sort, in turt sys.    12/11/13
I have a freshwater tank with 3 red eared sliders in it and I went and vacuumed the water and then as I refilled the tank I saw some red squiggly crazy freaking out worm with a type of pincher at the tail end and a mouth that looked like it was unhinging
<... not an Oligochaete>

or somewhat snake like as it was eating the floating crap that I stirred up when cleaning and refilling.. then I noticed with a closer look that there are a bunch of way smaller worm like things swimming around in there as well. These ones are harder to see because they are so small but are doing the same thing the big red one does, as in squiggles around completely looking like a crack head freaking out. Will these things hurt my turtles? I've attached a video of this crack head worm..
Thank you!
<Mmm, from your description these are likely some type of insect larvae rather than worms... But the latter are a possibility as well (from live foods, plants... see Darrel's rec. re "Koi" pellets as a standard diet)...
At any length, neither are harmful to turtles... Read here:
and the linked files above. Bob Fenner>

white worms in water... using WWM     8/13/15
I just did a water change today and noticed a whole bunch of tiny grey squiggly worms in both the dirty water I gravel vacuumed out in my pail and in my aquarium water. what are they and are they good or bad there in my aquarium? if bad how can I get rid of them?
<Read here: http://www.wetwebmedia.com/FWSubWebIndex/fwwormfaqs.htm
and the linked files above... or... use the search tools on every page. B>

worms, FW ID      8/19/12
hi WetWeb,
<Hello Jon,>
I have a question for the freshwater entomologist :
<Hmm… not exactly come to the right place!>
The other day I was watching a shrimp eating a dead shrimp. I guess it's normal for a shrimp population to somewhat control itself ?
<For sure. Or at least, to recycle calcium from moults or corpses.>
The number of shrimps seems to stay about constant but I don't see very many babies nor very many grandpas and grandmas.
<Pretty much true.>
Anyway, right near the dead shrimp I noticed a red wormy-looking thing. I've never seen this thing before. It was about the size and color of a bloodworm but not segmented.
<If it isn't segmented, it can't either [a] an insect larva such as a chironomid larva; or [b] an oligochaete such as Lumbriculus.>

Also, it slithered over the rocks rather than doing the bloodworm motion.
<Gliding over solid surfaces is more typical of flatworms, i.e., planarians.>
As I watched, it slithered away into the substrate never to be seen again. The substrate is round river rock of various sizes. Not too big but larger than normal aquarium gravel. Kuhli loaches love it. This thing was slithery like a slug, not free-swimming at all and rounder rather than flatter.
<Again, suggestive of a planarian.>
I searched the site and found Planaria and leeches but this creature seemed more evenly shaped than a leech, not fat in the middle with tapered ends.
<Leeches are segmented; they are of course Oligochaetes.>
And it didn't have the triangular head that Planaria have.
<Ah now, the triangular head with the two eye spots is not universal to flatworms.>
I searched and searched the rest of the tank but only see/saw the one.
Any ideas what this thing could be ?
<Does sound like a planarian; look at species such as Dugesia which are fairly common in ponds and get into aquaria via plants and live foods. They're harmless, by the way.>
thank you,
<Most welcome, Neale.>
Re: worms, FW ID    8/19/20

Thank you for the reassurance :)
They sure look nasty icky slimy but we probably aren't very attractive to them, either …
<Likely so.>
I'm sort of assuming that since this is part of life, as long as they aren't parasites they're actually good for the tank ?
<Or at least neutral. If you have a lot of them, then that tends to indicate the tank isn't clean (overstocked, uneaten food, inadequate maintenance). But a few of them is normal, and in some tanks adds to the charm of the aquarium. Indeed, I have an 8-gallon aquarium on a sunny windowsill that's crawling with tiny life such as these worms, and it's a useful place to grow on small fish like Ricefish fry that feed on algae and tiny animals. It's a fun tank to observe, almost like a reef tank.>
Especially since I've only seen one, not thousands ?
<Quite so.>
thanks again much :)
<Cheers, Neale.>

Tiny white worms 2/5/12
Hi Bob
I am not sure if you can help me but there seems to be some tiny little white worms crawling on the glass of my yabby's tank. I have attached a picture (not so clear).
Are these harmful at all to the fish and to yabby?
<Not likely; no. Their sudden appearance is not uncommon. With regular maintenance, being careful re feeding, they will just as suddenly go>
Your help is greatly appreciated.
<Read here: http://www.wetwebmedia.com/FWSubWebIndex/fwwormcompf.htm
and the linked files above. Bob Fenner>

Crazy little pink worms -- 08/13/11
Hello, WWM Crew!
I have a question about my desktop 1.5 gallon planted Betta bowl with blue aquarium gravel on the bottom.
<Filter? Heater?>
I live in Phoenix, Arizona, and I used local tapwater with BIO Safe and BIO Coat for water conditioners. I noticed a couple days ago that my 2 year old pet-store bought Betta was acting very funny. I figured it could have been a swim bladder issue (common, first time with him, not my first rodeo with the beast), but as I looked closer, I notice a swarm of flesh-coloured roundworms swimming throughout the water.
<These are segmented worms... Annelids>
They're a variance of sizes (1mm - about 15mm at the longest), and are not larvae of any of the common office--wide annoyances (all 3 parents are entomologists. I had a fun childhood).
Now here's the thing, I know they're not Planaria. Like I said, these are roundworms who kick and swirl around like miniature young Tubifex.
<Do look like Tubificids to me>
I was raising some Tubifex in a 2.5 gallon at home, but I never cross-contaminated these tanks.
<Someone did>
They don't breathe air. I believe they're too small to be hookworms. I can't get a good enough picture, but they're long, thin, hairlike, at a variety of height levels, seeming to prefer inhabiting my java ferns near the bottom. You can kind of see them wrapped around one of the roots in the pictures. They were flailing too much to get a good look at their head. They don't crawl on the sides of the glass. When I remove them from water, they turn light pink.
I cleaned his bowl thoroughly, was unable to remove the infestation, tossed the rocks, rinsed again, replaced the gravel. Then, as I was washing the java ferns, I reinfested that bowl, so, I'm letting it dry out. Meanwhile, my poor old Betta passed away (in a cleaner, different bowl, sand bottom). I got new plants, and it seems that I managed to move my Betta to the new bowl without cross-contamination, so it would suggest that they are not parasitic in nature to fish. I still have the old java ferns in a paper cup, and hope to eradicate them with an invertebrate-icide.
Any idea as to what they are?
<As stated>
Also, is there an invertebrate killer that is not harmful to plants?
<Read here: http://wetwebmedia.com/FWSubWebIndex/AnthelminthicsFWF.htm
Not worried about killing fish. These little guys will go in an uninhabited tank until these things are gone.
<And here: http://wetwebmedia.com/FWSubWebIndex/bettasysart.htm
Bob Fenner>

Re: Crazy little pink worms 8/15/11
Hi Bob!
<Hey Em>
Thanks for your answers! I've only ever taken java ferns from this Betta bowl home, never the other way around. Such a mystery. It's quite possible a Tubifex egg sac ended up in my bowl via tap water. I have since switched to our filtered water. I could do without another unintentional worm outbreak.
<Mmm, maybe>
I've been thinking of getting a Picotope for my desk so I can keep a filter and heater; currently, there hasn't been any room. I guess it's time.
Thanks again!
<Thank you! BobF>

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.>

Worm, Larvae, or other?    3/14/16
Hi There,
Just finished cycling a Fluval Edge 6 gallon aquarium after 4 weeks. I cycled with pure ammonia from Dr.Tim's Aquatics dosing 4ppm each day the ammonia read 0ppm. The tank is planted with Helianthus Callitrichoides,
Lilaeopsis Brasiliensis, Vesicularia dubyana, and a few Aegagropila linnaei. I dose with Flourish Comprehensive weekly and Flourish Excel daily with 12h/day lightning by means of my Finnex Planted+. The plants are all
growing wonderfully. There are also some snails that hitched a ride on the Java Moss
<http://www.fishlore.com/fishforum/aquarium-plant-profiles/114960-java-moss-care-sheet.html>  I purchased from my LFS
<http://www.fishlore.com/fishdictionary/l.htm#lfs> , which I don't mind at the moment.
I have yet to perform a water change
<http://www.fishlore.com/fishdictionary/w.htm#waterchange>  and will do so after I figure out what these pests are. First here are the water specs to get an idea of the conditions:
pH 7.0
DKH <http://www.fishlore.com/fishdictionary/d.htm#dkh>  4
dGH 4
NH3, NO2 0ppm
NO3 80ppm (as I said, have yet to do a water change
<http://www.fishlore.com/fishdictionary/w.htm#waterchange> !)
<You're disciplined!>
<Who? The worms I'll assume.>
have definitely proliferated in the past few days (probably due to increased nitrate concentration), with most coming out at night and wiggling erratically at the top of the tank. Few also float in the water column during the day. The majority are translucent with some varying with brown specks. The supposed worms appear to be segmented, which leads me to believe they are of the Annelid phylum or are larvae of some kind
<Likely so>
and therefore not Planaria, but then again I could just be seeing things.
Maybe they are some sort of Dipteran larvae?
<Can you send along a well-resolved pic? The two groups of invertebrates can be discerned on close inspection>
Please let me know!
<Please read here re identifying these groups:
Bob Fenner>
Re: Worm, Larvae, or other?    3/14/16

Oh yes! The most important part of the email was omitted! Here is a photo:
<Ahh; these appear to be insect larvae. I'd vacuum the gravel to remove them. Bob Fenner>

Re: Worm, Larvae, or other?    3/14/16
Thanks for the help IDing them! I am planning on getting a school of 6 cardinal tetras, so I hope they will find them to be a delicious treat.
<Which? I'd remove the larvae as stated... They may turn out to be fish eaters, or flying about your house...

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