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FAQs on Freshwater Worms of All Sorts, Identification

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, 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,

What's that on your plant? A leech!

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>

Can you tell me what this is please???      7/9/17
<Hi Kelly>
I am hoping you might be able to help me. I have indoor/outdoor cats and of course leave a water bowl out for them. Recently though I have been finding strange worm-like organisms stuck to the inside of the bowl. I've included a picture of one to show you. I would just like to know what it is and if it is harmful to animals. I appreciate you taking the time to read my email and thank you.
Kelly Michel
<Mmm; this looks like some sort of flatworm/Platyhelminth to me... Likely not an issue, but I would share this pic or better, specimen with your veterinarian just to make sure. Bob Fenner>

Re: Can you tell me what this is please???      7/9/17
Wow a flatworm?
<Yes; look in your reference works, the Net.>
Thank you very much for your help, and advice. I will be showing it to my veterinarian.
<Ah, good. BobF>

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 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...

FW Worm ID; no pic or rdg.     10/2/15
Was wanting to ask about a worm like creature I discovered in my tank internal filter inlet tonight it was about 3/4 inch brown in colour when I grabbed it it stretched to about 5-6 inches while attaching itself by a sucker mouth
<Ooh.... was going to key Oligochaete; now.... Hirudinean>
but only at one end though wiggling around attached to the glass as i couldn't get a grip I pulled it out got rid of it then I removed the fish some pregnant platies I planned to birth put them back in main tank the tank in question was used to temporarily house a juvenile breeding stock of expensive Plecos previously to this these have now moved to larger
setup along with some tetras and tank was empty of fish before the platies went in my main concern is will these be a risk of harm to the previously housed Plecos or have been transferred in anyway to the bigger Pleco setup if so how do I eradicate them also had a snail issue in this tank if you could advise me asap thanks Teresa
<Read here: http://www.wetwebmedia.com/fwsubwebindex/leechesfwf.htm
Bob Fenner>

White/clear "worms" in tank       7/19/15
Greetings. I just cleaned my daughters fish tank and the water I replaced it with came from a natural spring.
<Do check water chemistry. This isn't an ideal approach.>
After filling the clean tank I noticed there were hundreds, if not thousands, of small (about 1/4 to 1/2 in) white /clear "worms" (not sure if they're worms or some insect larvae).
My main concern is that my children and I drank from the spring before I realized these were in it.
<Apparently haven't done any harm so far?>
Anyway, just trying to figure out what they are. Any help would be greatly appreciated.
<From this blurry photo, not a chance. But nematodes, Nematomorphs, Oligochaetes and insect larvae are all possibilities. Grab a microscope (most high schools and colleges have these, if you don't) and look for the relevant features: segments and bristles for Oligochaetes, lack of segmentation for nematodes, and so on. Do you know Buchsbaum's "Animals Without Backbones"? It's a classic primer that covers the basics of each taxonomic group in adequate depth. Older editions (30s-60s) are extremely accessible to non-experts with an open mind.>
One other note, the fish in the tank seem to like eating these things.
<Indeed they will.>
Also some appear "dead" as they don't seem to be moving and others are definitely moving in a squiggly worm-like fashion.
<Your analysis seems reasonable.>
<Most welcome. Neale.>

Nematode worms       6/19/15
Dear WWM crew,
I happened upon your site following several searches to try and identify the worm-like creatures I found on the bottom of my outdoor swimming pool. I realize your site is for aquarium enthusiasts, but your specialists seem really knowledgeable about worms and larvae, unlike most of the drivel I find in "Yahoo Answer-like" web postings. Could you help identify the fast wriggling creatures in the attached video, <insect pool larv.mov> and recommend how I can get rid of them? They inhabit a 100ft long outdoor swimming pool for recreational swimming and most users would probably not like to share their swimming enjoyment with these creatures.
Thank you for your expertise!
Best regards,
Marc de Beer
<There isn't enough detail to say what sort of "worms" these are, whether annelids, nematodes, Nematomorpha or insect larvae. Nematomorphs are pretty common though, and generally harmless to us since they infect different sorts of animals. Unfortunately, chlorine levels in pools are not normally high enough to kill the durable eggs of some "worms", and insect larvae may appear repeatedly because the flies, mosquitoes and other species can come to a clean pool and lay their eggs there. In short, there isn't a one-shot chemical solution to these. Net them out, and in particular, remove potential hosts as quickly as you can to prevent possible reinfection -- typical hosts for Nematomorpha are insects including flies, crickets,
beetles and so on. Cheers, Neale.>
<From the motion of the animal in your MOV, am pretty sure this/these are insect larva/e... See WWM re. Bob Fenner>
Re: Nematode worms       6/20/15

Thank you so much!
Best regards,
<Simple chlorine shocking procedure will very likely rid your system of these larval insects. BobF>

Hair like worms ,not Planaria...      2/20/15
I've read everywhere that these worms are Planaria and harmless.
<They're not. These ones are almost certainly freshwater Oligochaetes.
Again, harmless, and likely in most mature tanks.>
I first noticed them when they were not there then they were literally within 20min I had probably 1000 or so, my whole tank looked like it was full of rice length hair thin worms. This happened on a Sunday. I cleaned the tank, rocks, plants, and all decore refilled ,treated and all was good. I layer off feeding (freeze dried blood worms) as much and less often to prevent over feeding....guess what, they came back, not as great in number but noticeable. I took a pipette and sucked a few up and viewed under a microscope at 50x they do not look like Planaria...they have feet. I need to know if these will kill my fish and how to keep them gone.
<No, they won't harm your fish. Dosing the tank with an anti-helminth medication (such as Prazi Pro) might eliminate them, but then, as has to be stated loud and clear, all medications are poisons, and using them needlessly is a potential risk. Will these worms do any harm? No, freshwater Oligochaetes are mostly scavengers or micro predators, consuming decaying organic matter and the very smallest of organisms. They are actually beneficial animals in most cases, though overfeeding or under-cleaning the aquarium may provide them with so much food their numbers multiply rapidly. A few wouldn't be anything to worry about though.
Cheers, Neale.>

See the segments?

Re: Hair like worms ,not Planaria...   2/21/15
Thank you so much. I actually put 3 of them in a drop of water to observe their behavior towards each other when their environment was constricted enough to force them to be in close proximity to each other and I guess like everything else in the universe, limited space creates much tension.
<As Frank Herbert liked to point out, the most severe threat to a species comes from its own kind, not from predators or competitors. Limit the supply of oxygen, as you did, and it's every man (or worm) for himself.>
They literally began fighting each other, attacking, biting and violently twisting up within themselves.
<I'd be wary about reading too much into what your little Shai-Huluds got up to in there. Lack of oxygen and rapid increase in temperature under a microscope can cause many non-unicellular animals to behave very aberrantly, reflecting the severe stress such warm, bright environments cause on animals accustomed to cool, dark places.>
I take pride in my little 20 gallon tank taking 4 hours to clean it when needed, bi weekly 20% water changes, conditioners and I don't use medical chem.s normally. I have tried a Mediflex treatment for a minor fin issue from nipping, which helped but I don't like running a no carbon filter for 7 days. I really appreciate your rapid response and setting my mind at ease. I love my little guys and feel they are more than just fish as one major pet store chain tried to convince me of.
<Yikes! Glad your enjoyment of the hobby has developed and become more rewarding than this particular retailer might have supposed. Cheers, Neale.>

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>

Fresh water worm 1/24/11
I discovered this worm swimming around the edge of a tank. It is a very small pink worm which wiggles very quickly as it maneuvers through the water. I have a 600 gallon Aquaponics setup in which I am raising Tilapia. Is this a harmless worm or something parasitic?
<Can't tell definitively from your photo, but highly likely it/this is harmless>
I recently added snails to my tanks for algae control. I am worried that it may have come from the snails.
What do I treat this with if it is harmful to me or my fish as I will be eating these fish?
<There are vermifuges of use:
Though again, this is not likely a species of worm that can/will cause trouble in cleaned, cooked Tilapia/Oreochromis>
Currently my fish do not appear to be sick in any way. I also use salt regularly in my tanks. I have attached a photo.
Please let me know if I need to take a better photo for your identification.
Thank you,
<Would need a better pic. Bob Fenner>

Re: Fresh water worm 1/25/11
Hi Bob,
I took a better picture for you as requested. When zoomed in you can see the body segmentation. Thank you for your time and prompt response.
<Ahh! Even more inclined to state that this animal is highly likely not-destructive... Is an annelid... Perhaps a Tubificid. Bob Fenner>

Re: your freshwater worm 1/25/11
Hi Bob,
> The beastie in question appears to be a freshwater oligochaete. Not uncommon, and completely harmless. Indeed, arguably beneficial if you're going for a rich, denitrifying sediment like a freshwater DSB.
<Ah, yes... is just so>
> Cheers, Neale
<And you, B>

Ftn. leeches?? 12/17/10
I have found small red worms that strongly resemble ones discussed on these two pages http://www.wetwebmedia.com/fwsubwebindex/tapewmfwf.htm
in a freshwater outdoor water fountain (with no fish). When I go to change the water every other day or so they float up and are swept out of the fountain and into the flowerbed. Birds use the fountain to drink and I imagine that mammals use it at night. I have red wriggler earthworms and décolleté snails in the yard also, but never find them in the water fountain.
My questions are;
Are they harmful to birds, cats or skunks etc?
<Can't tell with the information presented... All Leeches are parasitic...
can't/don't live long w/o hosts. Do yours show segmentation, suckers?>
If they are harmful how do I eliminate them?
<Simple bleach>
Is it possible to 'dose' the water to prevent their return?
<Depends on the source...>
I don't currently have a pet but when I did she did drink out of the fountain, when I get another will I have to prevent it from doing this?
Thanks, Pam Kelso
<Welcome. Bob Fenner>
Re: leeches?? 12/18/10
Thank you for the reply. In rummaging around the internet after I sent this to you I think that I have identified the culprits. They are midge fly larvae, bloodworms.
<Ahh! Quite common to have such insects w/ aquatic larval stages using water features opportunistically. And not a disease issue>
Because I clean out the fountain every few days I never saw them at maturity and they were always small and non-segmented. I know that we have midge flies so I think that solves it. Thank you for getting back to me so quickly.
Pam Kelso
<Welcome. BobF>

tiny crawlers, assoc. w/ terr. hermit 10/4/10
Two days ago I purchased a hermit crab for my child. To our surprise, the hermit crab had company today! There were tiny worms in the mulch-like substance that was recommended for the tank. I thought they may have been bristle worms( I know that they sometimes buddy up with hermit crabs in their shells), but your many descriptions do not match what these appeared to be. They were approximately 1/4" long and light brown in color. They resembled a very small earthworm. I apologize for not having a picture. I panicked, and dumped them. There were at least three of them. Do you have an idea of what they were? My next question is, "Are they harmful to the crab or my child?" Thank you for your time.
<In the mulch... Very likely these are/were not actually worms of any sort, but insect larvae... And other than being noisome, likely not harmful to your child. Bob Fenner>
Re: tiny crawlers 10/5/10

Thank you

Worm Identification 8/30/10
I found a worm in my drinking glass this morning. I assume it came in through my tap water. Could you help me identify it?
Thank you.
<It's not a worm; it's an insect. Some sort of Dipteran larvae, e.g., a midge. Harmless, and an excellent fish food! Cheers, Neale.>

Long skinny pink in color worms living in my grave, FW ID 3/25/10
Hi , I have a 28 gal bow tank. With drift wood and live plant's in it. Two stick fish,
<No idea what these are. Do you mean Pencilfish?>
two hatchet fish. I also have about 50 plus cherry shrimp and two bamboo shrimp. My cherry shrimp are breeding.
<As is their wont.>
But I have also seen what looks like pink in color or are skin color , long and very thin worms sticking out of the gravel in my tank. Do you have any clue on what these are and if they will hurt anything in my tank.
<Likely just freshwater oligochaetes, and not only harmless, but actually beneficial. Do read here:
Thanks Beth
<Cheers, Neale.>

Mysterious white worms (in a freshwater tank) 3/10/10
Good morning!
I am a first time WWM email user. And I find your website tons of help! I have a question. This morning I cleaned my fish tank and I saw tiny white worm-like creatures on the glass of the fish tank.
<Likely free-living nematodes and planarians. Not in themselves dangerous, but a sign that this tank gets too much food and not enough cleaning, since they feed on uneaten fish food (among other things). In most tanks you might find a few, but not enough to notice. If there are obviously lots and lots of them, then you have a problem.>
Also while I was using my siphon I stirred the gravel a little bit and 1-2 inch white worms and my angelfish and guppies started to have a feast, when I looked in my bucket I saw 50 maybe 100 of them and I'm worried. They swim in kind of a S shape and when they stick to the glass they move kind of like an inch worm. Kind of creepy.
<Just nature mopping up the mess you're making. Like cockroaches in a kitchen.>
I also tried a parasite med. But. I don't think that worked ;(
<Why would it? These aren't parasites. More significantly, trying to kill a bunch of animals in your aquarium means you're going to end up with lots of decay, and that means poor water quality. Imagine if you killed off a nest of rats with rat poison, but just left the bodies to rot. Bad. The correct approach here is to ignore the worms, and instead control their numbers so the population dies back over time. How do you do that? By limiting the amount of food they get to eat. Feed in sensible amounts, don't overstock your tanks, and remove uneaten food at once.>
Thank you for your time helping me!
<Cheers, Neale.>

Strange worm in toilet 2/16/10
for a while now we have seen a worm in our toilet that is a black worm with very thin white rings around the entire body. Nothing sticking out of it, pointed at both ends and very smooth looking. No one is sick in our family so have more or less ruled out a human parasite, but would like any ideas on what it could be and how it may have gotten into the toilet. I have searched the web, and found your site to have the closest information on it.
Thank you for your help.
<Jade, without a photo, it's impossible to say anything sensible here. It's most likely a fly larva of some sort (a "maggot" in popular parlance) and consequently harmless, though perhaps indicative of damp or decaying organic material somewhere nearby. Usually what happens is the maggot falls from above, so have a look for cracks and crevices in the ceiling. In any case, we're not medics or environmental health specialists, so any advice offered here is purely speculative. Simply in terms of the law, I'm sure I have to admit my ignorance, and recommend you contact your doctor first of all, to make sure it isn't a harmful parasite. Nematodes are very smooth worms that are pointed at both ends, and at least some are endoparasites.
Cheers, Neale.>

little clear worms in fish tank 10/7/09
hi I have a bunch of tiny clear worms in my tank and I was wondering if you can help me figure out what they are and how to get rid of them.
<Likely nematodes or planarians that consume uneaten food and organic waste. Although not harmful, they do indicate chronically poor hygiene, i.e., you aren't keeping the substrate particularly clean and/or you're allowing too much organic matter to accumulate in the tank. Clean the tank properly, and remove uneaten food and faeces, and the worms will die back.>
they are very small and clear, if the water gets a little low some will cling to the glass above the water. I notice some times when feeding the fish very small white looking flies come off the top of the water probably smaller than a fruit fly. when I clean the tank I such up as many of the worms as I can, but can't get rid of them. I have probably had them for a year they don't seem to hurt anything just a nuisance because my wife finds them little flies dead on the counter by our kitchen sink. tank is a 55 gal fresh water with a Texas cichlid and a Pleco. thanks in advance for your help.
<Cheers, Neale.>

The Worms Go In, The Worms Go Out.... 09/24/2009
My daughter has a 100 gal tank with fresh water fish in it and I have a 30 gal tank. Recently we found really tiny but long wiggly worm look things swimming around in our tanks. What we would like to know is what are they
<Without a MUCH more detailed description and preferably a good image, only guesses can be had. But I'd wager dollars to donuts that they are one of many harmless worms that can be found in freshwater tanks. Planarians, nematodes.... lots of possibilities. Of course, there is the less likely possibility that these are some sort of parasite. I consider this less likely because you state that they are "swimming around" in your tanks.>
and how do we get rid of them and keep them away?
<Well, once again, too little information to go on. I would guess that, like many other pest infestations, conditions are favorable for the worms and so they are proliferating. Make the conditions less favorable for them (reduce the amount of nutrients in your tanks) and the numbers should dwindle. Take a good look at your water conditions - Ammonia and Nitrite must be zero, Nitrate less than 20ppm. Do some hefty water changes if this is not the case. Siphon debris from the substrate, and check to see if your filter media might need to be changed - change it on a different day than when you siphon. Make sure the biomass in the tank is not too much for the tank or your filtration to handle.>
All of our fish seem fine but this is really baffling to us.
<Again, probably harmless. Remove the reason they're there (clean the tank, basically) and continue to do water changes as necessary, and their numbers will dwindle. You may never be "completely" rid of them, but they will likely become unnoticeable in very little time. Almost everyone's tanks have some sort of interesting life - worms and much more - and this is essentially normal. For them to be in such huge numbers as to be that noticeable to you basically just means there's too much "stuff" in the tank/water.>
We would appreciate any information you can provide us with.
<There are more options you can pursue.... Chemical means of eradication.... But these options are last resorts only, and will do more harm than good. Try upping your tank maintenance for a while and see how things go. I bet you'll find that they mostly go away on their own, with a clean, healthy aquarium. Let me recall to you a bit of a panicked experience of my own.... Some years ago, I had a smallish reef tank, 40 gallons or so. I had only one fish, and when I returned from vacation, went to check things and make sure he was doing okay. Though he was fine,
the tank was literally cloudy with worms - thin, long, squiggly worms - swimming about. As it turns out, the roommate feeding the one fish had gone against my rules of feeding him only twice while I was gone. The fish
(and thus the tank) was fed daily with far more food than the little guy could eat. There was debris on the bottom, and Nitrate tested unbelievably high. A large water change and two days later, the worms were basically
gone. I'm sure they were always there to an insignificant degree, but WOW, it was downright startling to see the tank utterly clouded with the things.
Makes my skin crawl just to think about it.>
<You're quite welcome.>
Very concerned, Mrs. Denise Petersen
<Hopefully I've at least eased your mind some, Mrs. Petersen. Best of luck to you, -Sabrina Sharp.... formerly Fullhart.>

What could this be???!!! Hirudinean 8/10/09
We live in rural Midwest Indiana (farmland). My boys go down to the creek and play in the water. (which has cow pastures nearby). Not sure that has any bearing at all.... but I just discovered this THING in my toilet!!!! I'm totally grossed out. It is dark colored, flat,....leach like
Any idea???
<It's a leech. Most leeches are harmless, feeding on invertebrates and the like. They are fascinating animals and you certainly shouldn't be "grossed out" by these little marvels. Some will bite people for a blood meal (a trait famously used in the past for "blood letting" but not used as a therapy after certain types of surgery). How this leech got into your plumbing is a mystery to me, but it is possible one your kids picked a
blood-sucking leech up when playing, and the thing fell into the water in the toilet bowl sometime later. It is very, very rare for them to carry diseases that can infect humans. People who have been bitten by leeches
typically have circular wounds on the skin with 3 distinct tooth marks. If you're concerned, place the leech in a jar of water, take it to your local medic to identify, and ask for assistance. Here at WWM we aren't qualified to offer medical advice. Cheers, Neale.>

Re: what could this be???!!! 8/10/09
thank you so much for taking the time to respond....and quick!
<My pleasure. Cheers, Neale.>

Identify Worm 11/23/08 I live in coastal SC and I kept my turtle tank outside during the summer and fall. I just brought it in for routine cleaning and because of cold weather. The tank had some strange "worms" that looked a little like "naked caterpillars with long string-like tails." The ones that were moving were a fleshy tan color. There were also some that were black or dark brown and very hard. Some of them were in the water but some were attached together by the "strings" and hanging off of a rock in the tank. I have looked on many sites and tried many different search terms but am not coming up with an answer. Please help me identify this strange little creature. Brandi <Hello Brandi. What you're describing is almost certainly a "rat-tailed maggot", a distinctive fly larva that inhabits stagnant water. The long "tail" is a breathing tube. They're pretty much harmless, and in England at least very common in small, unfiltered ponds. Fish (and likely turtles) don't seem to eat them, or at least my fish don't! Cheers, Neale.>

Little white worms in bathtub 10/14/08 I have been finding little white worms in the bathtub for about 5 days now. They are maybe 1/8 " long with a brownish red head on them. They are all different sizes sometimes smaller. I can't see where they are coming from. I looked in the ceiling and can't find any evidence. please help me. <My gut feeling is these are insect larvae of some type. Fly larvae ("maggots") often appear worm-like and commonly have eyes or heads sufficiently distinct enough in colour to look like what you are describing. Will likely be infesting some decaying animal carcass or rotten organic matter (like wood) somewhere nearby. Look around, initially working on the assumption the worms are falling downwards, either from the ceiling or via the plumbing. Best advice is to collect some of the worms and show them to someone qualified at identifying/controlling household pests. Cheers, Neale.>

help! Little wormy things 9/25/08 Hello, I just realized that in my baby guppy tank that there are these hair like worms that I can barely see. They are always vertical and they squirm around like a snake. Umm...they are white and they are about 1/8 of an inch. Are there any medications? I don't want to lose all of my baby guppies. Please reply quickly! -Sarah <Almost certainly harmless nematodes of some sort. They do thrive in dirty tanks, so seeing them is more likely a warning that you don't keep your tank clean than anything else. Cheers, Neale.>

Worms 09/04/2008 Hi I have a 29 gallon freshwater tank it is a fairly new tank only been up for about 7 weeks.. I just got done battling Ick on my swordtail fry and then today I noticed these brown worm looking things on the glass of the tank near the top ,but they were not in the water at the time I found them they were actually just above the surface.. I wiped them off but not sure if they are a worm or some type of insect larvae.. I have attached 2 photos, not the best because they are very small.. I tried looking it up myself but all I can find is references to white worms which these are not white.. Are they harmful? I already did a 20% water change while vacuuming the gravel today.. Thanks Trish <Hello Trish. The "worm" in question appears to be an insect larva. Certainly to my eyes it seems to be segmented and possesses small appendages of various types. In other words, a maggot. No immediate threat to the fish, but a good sign that there's a lot of decaying organic material somewhere in or around the tank. Otherwise the parent fly (or whatever) wouldn't have laid its eggs here. So time for an early spring clean! Cheers, Neale.> Re: worms 09/04/2008 Thank You.. I did vacuum the gravel out today after finding the worm like things.. and there was a lot of food in the gravel.. I didn't realize I was overfeeding , I only feed them once a day but I guess I need to cut down on the amount I am giving each day.. Thanks so much for your speedy response. Trish <Hi Trish. Overfeeding is easy to do, and much more difficult than to under-feed! Remember the two golden rules: Firstly, little but often. Snacking is better than gorging. The fish are more likely to eat all the food, and they'll also extract more nutrition with less wastage. Secondly, use the minimum quantity, and it should all be gone within a minute (for the average greedy community fish). Remove anything leftover; a turkey baster is a great tool for this, allowing you to pipette out stuff without buckets or getting your hands wet. Cheers, Neale.>

"Slash" our Oscar, concerns w/ "worms" in the tank 8/12/08 we got an Oscar about 4 months ago, and he has come around pretty quick! he is an amazing fish, as he is our first Oscar. he has had these little "worm" looking things on the inside of the tank, they are extremely small, and move around. they have not attached to him, and don't seem to be bugging him, but they are driving me absolutely crazy!! we feed him a high grade pellet food, and about 1-2 times a week he gets frozen treats like meal worms, or brine shrimp. he is in a 55gal tank, with a power filter for 50-60 gal (up grading to a canister filter), we also do about a 30 % water change weekly. I know its hard without seeing it, but what could these "worms" be? and how the heck to we get raid of them!? thanks for the help!! Desiree, Todd and "slash" <The "worms" are most likely Planarians, in other words flatworms. They feed on the food you've given the Oscar. As you know, Oscars are very messy fish. The fine particles they produce get everywhere, especially if the tank is inadequate and water changes are infrequent. In both regards, you're at fault here: cichlids need BIG filters, and you should be using a filter offering NOT LESS than 6 times the volume of the tank in turnover per hour. Forget about the rating on the box telling you X filter is for Y sized tank... these estimates are based on best-case situations where a tank contains few, small fish, Neons for example -- not Oscars! You also should be doing AT LEAST 50% water change per week, with the gravel cleaned on a regular basis. It's the stuff you're not removing that the Planarians are eating. While harmless in themselves, they're a "wake up call" telling you of an underlying problem. Long term, excessive nitrate in the water will lead to issues such as Hole in the Head that are a real bother to treat. So please, upgrade your tank (too small for adult Oscars), upgrade your filter, and step up the water changes. Do this and the Planarians should fade away in time. Do see here: http://www.wetwebmedia.com/FWSubWebindex/oscars.htm Cheers, Neale.>

PLANTED TANK WORMS - 7/24/08 I spotted this tiny brown worm on three of my freshwater aquarium plants this morning. Some are so small they look like dust. I removed them all with a turkey baster. My research didn't turn up anything. Can you identify them by the attached photo? Should I be concerned? Thanks for any help you can give me. You guys do a great job. Bob <Hi Bob. The photo is a bit small to say anything sensible, but my guess (and that's all it is) is that this is nothing more serious than some sort of insect larva. Common enough in freshwater habitats, but usually get eaten by fish if they end up in aquaria! In any event, very, very unlikely to cause any harm. If you're concerned, remove them and feed them to your fish. I'd be tempted to rear them in a small container of water just to see what they turned into. They aren't mosquitoes or anything noxious like that. Cheers, Neale.>

Re: PLANTED TANK WORMS Thanks Neale! <You're welcome, Bob.>

Worm Identification 4/17/08 Good Afternoon, <Jerry> I've searched the net and can't find an identification for what I've found. The Agricultural Extension in my count cannot identify it either and they have the only one of what I found. Here is a description of the worm and where it was found. The worms were each about 1 1/4 inches long and 1/2 inch wide. They rather looked like an adult human beings thumb. They were of a dull grayish color. One end was tapered and the other had a flat surface with a "lip," for lack of a better biological term, all around the flat surface. The flat end vaguely resembled what I've seen as the end of a tapeworm that has the hooks on it. These were found in a small bottle of 6% acidity Balsamic vinegar that was in a dark cabinet for about 3 years. They appeared to be dead, but I don't know. <Me neither... do you have a means of making, sending a micro-photographic image?> My agricultural extension said they were "vinegar eels," but when I checked on line, vinegar eels are long and stringy looking. <A general term for a few species of acid-environment nematodes... Some are cultured as fish food for fry...> The folks at the agricultural extension disposed of everything. I'm really upset about this because, although I haven't every seen anything like this around the house, they could be elsewhere and I'd like to know what I'm dealing with. <Mmmm, not everywhere... But this phylum is very common in the biological world... Take a read on the Net...> By my description, is there anything that you can tell me. I very much appreciate your efforts. Thank you, Jerry Ascione <Can only guess... sans more information, image work. Bob Fenner>

Re: Worm Identification 4/18/08 Mr. Fenner, <Jerry> Thank you for your really quick reply. As it turns out, the agricultural agency disposed of the "worm" after they took a biopsy from it, but they didn't tell me that. It turns out that it wasn't a worm. It was, as they called it, "Mother of Vinegar." <Interesting: A chemical/physical manifestation: http://en.wikipedia.org/wiki/Mother_of_vinegar> They agreed that at first glance it looked much like a worm and even had a texture that would be consistent with that of a worm. But, it wasn't. Again, thank you very much for your time. Jerry Ascione <Thank you for this follow-up. BobF>

Leeches in my Discus Tank -03/28/08 I have attached a picture of what I believe to be leeches after much research. They are living in the gravel of my fully planted 80 gal discus tank. All water conditions are within specs for discus and the discus and plants are growing like crazy. I have been feeding the live black worms, do you think they could have come from them? What can I do????? Please help. Thank You Deb <Hello Deb. Yes, those are leeches. Contrary to popular belief, the vast majority of leeches do not eat blood. They are certainly predators, but they go after small prey such as insect larvae and molluscs. It is very likely that the leeches you have are harmless towards your fish, and most probably came in with the live food you have been using. A little time spent with a book on native freshwater invertebrates will probably yield sufficiently accurate identification for you to decide if this is a safe species of leech or not. As a precaution though, you might elect to remove them to another aquarium or pond. It probably goes without saying that large carnivorous fish (e.g., puffers) will happily eat leeches. Alternatively, why not set up a little "critter" aquarium just for them and any other small beasties like shrimps and snails you across? Such tanks don't need heaters or lights, and a sunny (but not south-facing) windowsill is usually a fine location, allowing for some floating aquatic plants and algae to be kept as a base for the food chain. Such tanks are great fun, being more like reef tanks than anything else. Cheers, Neale.>

George in Greece... worms, copepod... ID 03/16/08 Dear Bob, As you can see in the photo there are two types of worms and one type of copepod (freshwater). <Can barely make these out> We are extremely interested in finding out the following: a) species and if not, genus or even family. b) are they harmful to fish (esp. fry) Your response will be greatly appreciated. George & Marina <The blue thing is obviously some sort of dipteran larva; the red things perhaps small oligochaetes, but it's difficult to say. In either case they're fish food rather than a problem! Fish fry *might* be harmed -- I've lost baby Corydoras to planarians, for example. But I suspect that the usual problem is that if the water (or substrate) are "dirty" (bacteria-laden) enough to support these small life forms, newly-hatched fish are at greater risk of fungal infections. So in my case at least, the planarians didn't kill the Corydoras fry, but simply attacked the moribund ones. That'd be my guess, anyway. Cheers, Neale>

Leeches??? Hi <Hello> I have had guppies for a few years and not experienced any problems. A few months ago I added a small Pleco followed by two elephant nosed fish. Shortly after introducing them to the tank I developed white spot. <Hopefully your fishes... not you!> I managed to cure this but lost a few guppies and one of the elephant nosed fish. I since read up on the elephant nose fish on the internet where it said not to keep them in pairs as the weaker one would be killed by the stronger. <Yes, very often... particularly in small systems> Since I have had all of these problems, I did a gravel clean and disturbed only what I can describe as a leech. It was about an inch long, white and had a sucker. At first I thought it was a dead fish. All of the info I have found on leeches describe them as fairly small and I have not found any of this colour. This leech (?) is bigger than some of my guppies. I cleaned the tank and a couple of days later found another one. I know they can be introduced by new fish... <Or live food/s> ...but surely I would have spotted them when I bought them. How can I determine that it is a leech and if so make sure there are not any more, I am really unsure of what to do. <Mmm, you could look at them carefully... leeches/Hirudineans are pretty distinctive... Take a look on the Net re: their superficial morphology... from your description already, I am pretty sure this is what you have> Can you please help? Many thanks <By thoroughly cleaning, gravel vacuuming your tank, you have very likely removed all the leeches from your tank. There are chemicals that to a large degree will poison just these worms... but I would not use them. Bob Fenner> Freshwater Bristle Worm? Hi, I hope you can help me! I used to keep a marine tank about four years ago and gave up and said that was it no more fish. Well now I have set-up a small freshwater tropical planted fish tank, it has been running for about five or six months now. My question is we have seen the fish go mad over a worm found in the tank, it was about two inches long, alive and being eating by a small angle fish and a Congo tetra. This worm was identical to the bristle worms we had in our marine tank but did not think you could get them in fresh water is this correct? <Yes> But how could it get there as we have not added any rock only dry gravel plants and fish. And could these cause problems to the tank inmates? < There are lots of little freshwater creepy crawlies that come into a freshwater aquarium. Usually they come in as eggs or larvae attached to the plants. They grow to a point until the fish realize that they are around and soon become live food. Some become parasitic on fish but I think you would have seen them by now.-Chuck> Kind Regards Grahame Brown

What worm be this? Planarian? >>Good day, Michael, Marina to help you here. >I started only 3 weeks ago and bought the following : a.. 3 small fantail goldfish b.. Plexiglas tank (4.5 gallons) c.. air pump d.. submerged power filter (mechanical filtration only) e.. gravel siphon cleaner I treat tap water by allowing to stay in a bucket for 24 hours and before carrying out a partial water change I add dechlorinator. >>Very good. >I usually carry out water changes of 50-80% every day but I am planning to build a Plexiglas tank of 70 gallons capacity and add another goldfish. Tanks in Europe are very expensive -- I bought the 4.5 gallon tank for USD 68 (Euros 57). >>Holy canoli! >Once a week I clean the filter element of the power filter. During the 3rd cleaning I noticed many small red worms in the filter element which were clinging in the sponge and could not be removed by washing with tap water. I fitted a new sponge element in the filter. The biggest worms were about half an inch long -- please see attached photo. Can you please advise if these worms are dangerous for my fish and how can I treat the water so that they will not appear again? >>The photo is not very clear, but I am guessing some sort of planarian. I do not think they will pose any threat to your fish. I have not had any experience with them, but I think that if you added some salt to the tank it would be enough to prevent them. This is actually a help to the fish, and is helpful in preventing or alleviating the incidence of some maladies. Use either Kosher or sea salt (anything that has not been iodized--very common here in the States), at a ratio of 1 teaspoon/gallon. I believe that one teaspoon U.S. = roughly 5cc. And 1 gallon (US) = 3.8 liters. I do hope this helps, and best of luck to you in sunny Athens, Michael! Marina (in what is *supposed* to be sunny southern California, but it's 62F and RAINING here! What first day of summer??)

What are these things?? More planarians? Good evening crew. <Good evening, Susan! Sabrina here> I sent the following message Saturday but haven't seen any answer as of yet'¦.soooo I thought I might try again. Know you all are busy but any help you can give me would be much appreciated. <I'm so sorry I wasn't able to get back to you last night; I've been battling an illness in my wild angels and totally stressing about it, so I've been quite preoccupied.... many apologies> Since I sent the request I have been doing as much research as I can. I'm now about 99% certain these guys are planarians and I know they are supposed to be 'harmless' but I also understand they will eat eggs. <What I know/can find, planarians really are harmless, and I've never heard/read about them eating eggs, but I'm certainly not positive about it. Can you describe the worms? You mentioned in your original message that they were white, flat, wider towards the middle, and about 3/4 of an inch long. The size alone is suggesting to me that they may not be planarians, which (from my understanding) are typically 10mm or smaller. Do they have a "V" shaped head? That's pretty much a dead giveaway that they are, in fact, planarians.> I would really like to get rid of the planarians before breeding my fish. <I can certainly understand!> Also, I inadvertently spread the problem to my 30-gallon community tank by 'seeding' the smaller tank with mature filter media from my big tank. <Oh, ugh....> This happened before I knew there was a problem in my 125G. I also forgot to mention that we are on well water if it makes a difference. <Mm, possibly, but I wouldn't think so. Worm infestations can happen in tanks that use the best of water. Usually, huge amounts of worms are the result of overfeeding, or otherwise excessive nutrients, and most often seen in predator tanks, like yours (several large predatory cichlids, an electric catfish, and an ever-messy Plec, in a 125 gallon tank, yes?). Try cutting back extensively on feeding for a while and see how that affects the worm population. Also, keep up with hefty gravel vacuuming to see if you can pull some of the little suckers outta there.> I treat any new water (with Prime) before adding to the tanks. Even though we test our well'¦.you just never know. I have talked to the three LFS I patronize and two advised Copper... NO WAY was I going to put this in my tanks. <Ugh! No.... Avoid this desperately! Especially with your scaleless Plec and catfish. Bad LFS, bad! Deserves a swat on the nose!> One finally suggested a fluke eliminator. But he was a little hesitant and unsure so I haven't done anything except vacuum and perform water changes in both tanks and cut the food by ½. <Ah, yes, perfect. Keep it up for a couple weeks, and see what happens with the wormies. Also, I'd like to mention that I had the occasional planarian showing up in my plant tank (well, lots of 'em, really), and they seem to have been eliminated by a very minute amount of Fenbendazole (proprietary name Panacur) that I used to rid my tank of (shudder) hydra. I certainly haven't seen a single planarian (or hydra!) in a month or two. But then again, my planarians were about 2-3mm long. Tiny. The Fenbendazole did not affect my bacteria bed in the slightest, nor did it have any effects on any plants, shrimps, or fish. It is usually sold as a goat-worming medicine, but can even be used as a wormer for discus.> My water parameters have not changed and all the fish are fine. I still have all 14 new Platy babies and they are growing like crazy. And I still have a gazillion 'creatures' that give me the creeps. <Well, keep up with what you're doing, for the time being, and see if the worms start to die out. I'd also like to mention our chat forum http://wetwebfotos.com/talk/ as we have rather recently had another fellow with a similar problem - perhaps you guys can compare notes.> Thanks in advance for any assistance you can provide. <Glad to help, and again, sorry for the late response!>

Planarians Hello. <Hi. Sabrina with you today.> I have a 20 gallon cichlid tank with a Fluval 4 plus filter very good water and pH, NO2, NO3, KH, GH. <I assume ammonia checks out, too? Can you give us your test results for your water parameters?> Same problem back again with little white worm type things on glass front and sides and back. Tried salt and methylene blue and they seemed to have gone. Two weeks later they're back again, about 50 of them. When I have the light off for a day they're all out on glass but soon as I turn the light on most disappear only 5 or 6 left on tank front. <These are probably planarians. Harmless to fish, these show up usually as a result of overfeeding.> One of my keyholes has red marks around face and did have a bit of fungus on side fins but gone now with MelaFix, but red marks remain. All fish rubbing on rocks and flat stone. <All of this might be attributable to water quality issues/overfeeding - how often do you do water changes? Gravel vacuum? Clean out the filter?> Please can you give help on what they are and how to get fid of them? <Do some good sized water changes, and some rigorous gravel vacuuming. Check your filter and clean. Decrease the amount you feed your fish for a while. This should all help reduce the amount of Planaria, if that is in fact what they are. Basically, when their food source is gone, they'll be gone, too.> I don't know if they're parasites or something else. The worm things are about 1 cm to 1 1/2 cm long white thin body. <Planaria are particularly easy to tell, with their classic "V" shaped head.> Thank you for your time.

Planarians - Part 2 Good evening Sabrina <Hello again, Susan!> Thanks for responding so quickly! I do hope you are successful with your angels. My research of Turbellarian flatworms (freshwater planarians) indicates they can be up to 1 inch in length. I was able to capture one of these little buggers and compared it to pictures found at www.planarians.org and it looks like the picture. Yes... they have a V shaped head (upside down V ). <Yeah.... "V" shaped heads almost always mean planarian, IME.> For now I am going on the assumption they are planarians and I am trying to obtain some Panacur. However, I am a little uncertain about the dosage. Somewhere on the Internet I read that the dose for hydra is 0.5 grams per 100 liters. What dosage did you use? <Honestly, I used so little, I don't know the actual dose. Likely less than a gram in my 72 gallon tank (filled to ~60 gallons). It took a couple of days to wipe out the hydra completely, and I'm really not sure about whether it nailed my little planarians or not, but I used to see 'em frequently, and since treatment have seen none.> Assuming that I treat both tanks this will work out to about 3 grams of Panacur. Also, do you think I can safely use this in the tank with the Platy fry? <Possibly, but if you can, perhaps wait a couple weeks for the fry to grow up a bit, if you can, just to be on the safe side.> I worked on the large tank some more today...moving rocks, vacuuming, cleaning the pump lines and changing the water. Didn't see as many critters today, so maybe I am getting them under control. <Hope so! Sounds like you're doing a good job of reducing their chances of getting a meal, so they may very well die out on their own. Give it some time, and keep doing as you're doing, especially if you think you're seeing results already.> Thank you again for your help. Susan <Glad to be of service! -Sabrina>

Planaria, or Parasites? I have 2 10 gal. tanks with feeder guppies that have been breeding. There is a parasite in the tanks that looks like a clear, small leech. What do I need to do to clear the tanks of these "leeches". Our local pet store told us that these are probably beneficial parasites that the guppies will feed on, but this information was supplied without their seeing the parasite. We have not seen any of these on the fish themselves but on the sides of the tanks and in the filter. Please advise. <Well, if they're not attached to the fish, if they're only on the glass or other areas of the tank, I doubt that they're parasites of any sort - "parasite" means that it's something that attaches to or lives in the fish and hurts the fish. What you have are probably Planaria. A planarian is a small worm, usually just a few millimeters long, and are best identified by a "V" shaped head - take a look at this: http://www.naparcd.org/planarian.htm . The presence of these little wormies suggests an overabundance of "stuff" in your tank that they are feeding on. To get rid of them, simply eliminate their food source - more frequent water changes, being sure to vacuum the gravel, and cleaning out the filter will help with this. They are essentially harmless, but it'd be a good idea to clean up the tank a bit to reduce their numbers or eliminate them completely. Hope all goes well, -Sabrina> Janet

Small worms in freshwater tank (11/06/03) <Hi! Ananda here this afternoon> We have a 29 gallon regular fish tank, we have 2 angel fish and some small plants, lately the water has started turning green and now we have some kind of small worms on the inside of the tank and was wondering what they are and what we can do about it? <Well, the water turning green is an algae bloom. That's usually triggered by an excess of nitrates and phosphates. To combat that, you'll want to do more frequent water changes. Also make sure you aren't over-feeding -- if there is any food your fish don't eat, it adds to the phosphates in the tank. You might get a phosphate test (I like the SeaTest/FasTest one for freshwater) and some phosphate remover (like Phosguard) if your phosphates are high even after several water changes. Once you get the nutrients (nitrates and phosphates) out of the tank, the algae should die off, and the worm population should decrease. I'm not sure exactly what you have, but they are most likely not harmful for your fish. --Ananda>

Lair of The White Worm! Do you know anything about white worms. in freshwater tanks. <These are Planaria. Planaria are flatworms and members of the Platyhelminthes phylum. Planaria are often found in aquariums with uneaten food. The Planaria won't hurt the fish, but they are a symptom of too much gravel containing too much uneaten food, and that is not good for fish. You should do a water change and vacuum your gravel to help remove the uneaten food and some of the worms. Doing this will reduce the number of worms in your tank. Good luck -Magnus>

White Worms, and a Bit More Info - III - 02/10/2004 Ok I put some food in the tank and the lobster never ate it. So I got worms from uneaten food. Now there are a lot of white worms in my tank little white ones. <With this as the most (only) information that you've given us, I can guess that you probably have some sort of nematode or Planaria infesting the tank.... not so much a direct threat to the crayfish or other inhabitants, but a sign of less than adequate husbandry.... Do not overfeed, be sure to remove uneaten food, change water regularly, vacuum gravel properly, change filter media as necessary.... basically, remove the food and nutrients that is fueling these worms, and they will gradually die off on their own. On such little info, that's the best I can give you. I hope it helps. Wishing you well, -Sabrina>

White Worms In Gravel Hello, I have a 55 gallon aquarium and have noticed small white worms in my gravel. The fish I have in the tank are guppies and two Plecostomus. I have had no problems until now and just need some advise to get rid of them. Thanks, mike <<Dear Mike. It sounds like Planaria, in which case, you will also see them on the tank glass. This is generally caused by overfeeding. Cut back on the feeding, vacuum your gravel with each water change, and this problem should rectify itself quickly. Some fish, like Gourami's, will eat Planaria. However, you do need to be careful to keep your tank clean, and keep up with your regular partial water changes. HTH -Gwen>>

Re: Tiny white worms in my aquarium - II Hi Gwen, Thanks for the info. I don't think I've been getting deep enough into the gravel when vacuuming, even though my water changes have been several each week, approx 20% each time, I think I will have to vacuum more thoroughly. I saw a cardinal tetra eat one of the worms that I knocked off of the glass when cleaning tonight. Thanks so much. Mark. <<Mark, you are most welcome :) -Gwen>>

I think I have Worms Hey, AGAIN sorry to be such a pain I realize you guys got lots of letters. Anyway I got these worm like things in my tank well they look like very very tiny maggots all most they are like 3 mm long and very thin are they parasitic? please get back to me. Thanks for reading, Aaron <<Dear Aaron, they sound like Planaria. Are they on the glass? Is this a freshwater tank? This is generally caused by overfeeding and improper maintenance. Try to cut back on the amount of food going into the tank, and make sure you vacuum thoroughly with a siphon when you do your water changes. Once a week is a good idea, specially till your worms go away...which they will when they no longer have a food source. -Gwen>>

Strange red worm like thing Hello <Hey Lukas, MacL here with you on this fine day.> Lukas here. I have recently observed a odd looking red worm like things at the bottom of my 90 gallon and on some of my plants in my Betta enclosure. It seems to be growing at the top of the Betta tank on some plants. <Sounds like algae to me.> But in my 90 gallon its at the bottom around the gravel. I try to suck this stuff up when I do my water change but it keeps coming back. If you need a pic I can get you one on Tuesday. <Pictures definitely help, send it to me if you don't mind.> What is this stuff and is it bad for my fish? Thank you L White worms crawling on the glass of my aquarium I have a 90 gal. tank with four discus in it which is also planted. I have noticed what appears to be small white worms crawling on the glass and swimming freely, can you tell me what they are? <Not specifically... as in down to species. But I assure you, these are likely some sort of innocuous earthworm-like animal (oligochaete annelid) and not harmful to your fish or system. These sorts of critters "pop-up" quite often, particularly in aquariums that have excess food, too little circulation/filtration... and very often "disappear" of their own accord. Do keep your eye on water quality and in time you will likely find they have gone. Bob Fenner>

FW worm 6/23/06 Hi Bob. I have a tank with an African brown knife, mollies, ghost cats. This morning I saw what appears to be a tiny, tiny black worm crawling at the bottom of my tank. What can this be? <Mmm, could be an oligochaete (something akin to an aquatic earthworm)... even a Hirudinean (leech)...> Everyone is eating & appears healthy. Water is good. Thanks! Diana <What is that Ted Nugent lick? "Where in doubt I take it out... it's a free for all"... I would remove this mystery creature just in case. Bob Fenner>

Not urgent. Calcium, and worms. 11/01/06 Hello Crew! <<Hi, Rachel. Tom>> I know you're all terribly busy, and this isn't terribly important, so please feel free to skip over this one! <<Can't do that Rachel. Yours is important to you which makes it important to us.>> I have a 2.5 gallon tank with a 25-watt heater, 10-watt fluorescent lighting, and in-tank Whisper filter set on low, in which I keep a spoiled-rotten Betta of about a year and a half old. The system was started about a year ago, and was moved/remodeled two months ago. About a month ago I added a Java fern and some red Ludwigia. I added a lovely blue mystery snail (Pomacea bridgesii) a week ago, and he is doing a remarkable job on eating the algae (working on getting the plants to thrive instead!). <<I completely understand'¦>> Temperature is 80, ammonia and nitrite 0, nitrate usually under 5 now since adding the live plants... I think the pH is 7.4, though I'm not at home right now to look it up. I try to do 25% water changes every week or two, though I've been lax lately. Anyhow, my water is on the soft side, and the snail's shell is already looking a little worn. I am planning to add "something" to the tank for calcium. I've heard of crushed coral or marble. However, since I also keep a cockatiel, I have cuttlefish bone handy as a source of calcium for the bird. Could I put a well-rinsed (and obviously unused) piece in the aquarium? <<I've not run across this for aquatic snails but I have for land snails. Frankly, I find it a good option to try especially given that your pH is already at ~7.4.>> And how big a chunk are we talking? <<Try a piece with a surface area of about one square inch, or so.>> The bones are about five inches long by two or three inches wide, half an inch thick, and can easily be snapped into smaller pieces. Was just planning on tucking it behind a rock somewhere with a little water flow to help it dissolve. Right? <<You might find that your snail will actually 'feed' on the bone as land snails do. (I'm somewhat curious about this myself.) Obviously, you'll want to monitor pH levels though I don't believe that this should prove to be a problem.>> Secondly, I've noticed "the little white worms" floating around and wiggling on the tank walls. White, threadlike, about 1 cm long. I had these once maybe nine months ago. Up until yesterday I was assuming they are harmless Planaria, and I was stepping up the water changes as I know these are a sign of excess nutrients. However, yesterday I noticed Terrence the Betta eating them as they floated by. If they're just free-living Planaria I'm pretty sure this is harmless, but is there any chance these could be parasitic worms which Terrence has passed and he is re-infecting himself somehow? <<Parasites, by definition, require a 'host' in order to survive. In all likelihood, they're Planaria.>> His feces are never stringy-white, but very occasionally his normal feces will include some little clear sections that look like mucus. I believe I'm just paranoid, but better safe than sorry! He is acting quite normally, swimming around, flaring and nipping at the snail, eating voraciously -- he has even started to pick at the algae wafers for the snail, and will steal them out from under him! <<Don't be overly concerned about the occasional clear sections in his feces. This isn't uncommon or an indication of a problem any more than a very occasional sneeze means you're getting a cold. Just happens'¦>> Thanks for all your hard work! Rachel North Carolina <<Thank you kindly, as well, Rachel. Best regards. Tom (Michigan)>>

Round worms in swimming pool 12/11/06 I know this isn't a typical question you get... but.. thought you may be able to help. We have a salt-water swimming pool and we recently noted 2 worms in the pool we've never seen before. They were about 7-10 inches long, round (not flat), very very thin (think 0.5mm pencil lead). They were swimming just fine in our hot tub - the water was not hot. When we brought them out of the water, they flip flopped around somewhat spastically with both ends moving independently. There were a brown-ish/yellow color. Their skin/skeleton was quite "crunchy" when we tested to see how tough it was. :) Any idea what this could be? -Bruce <Mmm, as you state, could be Nematodes... if you have a good magnifying loupe, you could cut through (make a coronal section) through the esophagus (just a bit back from the head...) and look/see if this is tri-radiate (three-sided)... diagnostic for the Phylum... could be Horsehair worms... other "wormy" possibilities. Not toxic, or dangerous to human health assuredly. Bob Fenner>

FW Plant Leech 03/23/07 Hi Crew! Hope all is well with you, you've helped me so much in the past. To make a long story short, I have a 10 gallon tank that has been used as a plant refuge for when I thin plants out of the aquariums. I throw them into this tank. At one time the tank was a failed attempt to raise daphnia, I never cleaned it out after that, just started throwing plants into it. After a few months I was given some cherry shrimp that were too small to go into the main tanks, so I put those in there. When I added the shrimp I put in a sponge filter and heater. I don't perform routine water changes on this tank. This tank has been a fascinating biological experiment of sorts because it has a blanket of live Blackworms now that must have accidentally come in there on plants. (I feed the fish live Blackworms a couple of times a week.) The tank is full of shrimp that have bred like crazy and hitchhiker snails. The water is green, and amazingly there is no algae in the tank, whatsoever. However, it is time for me to transform it into a usable tank and I was thinking of putting a couple of Killies and a group of sidthmunkis in there, of course making sure the parameters are good first. I really wouldn't want to see all of this "food" go to waste. Sound like a good idea? Probably not... But anyhow, I also have these in my tank. Do you have any idea what they are? Are they good slugs/flatworms? Or bad slugs/flatworms? Should I just forget my dream of giving some lucky fish the feast of their lives and clean the tank out before I introduce any fish into it? Thanks! Take care, Mary. < This is a typical FW plant leech. Fish don't eat them but they really aren't much of a problem.-Chuck>

FW Plant Leech, Neale's go 03/23/07 Hi Crew! <Hello Mary!> Hope all is well with you, you've helped me so much in the past. To make a long story short, I have a 10 gallon tank that has been used as a plant refuge for when I thin plants out of the aquariums. I throw them into this tank. At one time the tank was a failed attempt to raise daphnia, I never cleaned it out after that, just started throwing plants into it. After a few months I was given some cherry shrimp that were too small to go into the main tanks, so I put those in there. When I added the shrimp I put in a sponge filter and heater. I don't perform routine water changes on this tank. This tank has been a fascinating biological experiment of sorts because it has a blanket of live Blackworms now that must have accidentally come in there on plants. (I feed the fish live Blackworms a couple of times a week.) The tank is full of shrimp that have bred like crazy and hitchhiker snails. The water is green, and amazingly there is no algae in the tank, whatsoever. <Because it's balanced. In balanced tanks, the rate of algal growth is checked by the growth of plants and predation by algae-eating animals. In aquaria (and ponds, and eutrophic waters in the wild) the balance is lost, and often the algae prosper because their natural limiting factors are taken away.> However, it is time for me to transform it into a usable tank and I was thinking of putting a couple of Killies and a group of sidthmunkis in there, of course making sure the parameters are good first. <You'll lose almost all the fun, I suspect. To reach a balance with fish, you need a *lot* of water volume per fish. Look for a copy of the excellent book "Dynamic Aquaria" for a scientific (and highly detailed) investigation of balanced aquaria with complete ecosystems. Certainly possible, but very challenging if you include fishes, miles easier with just inverts.> I really wouldn't want to see all of this "food" go to waste. Sound like a good idea? Probably not... But anyhow, I also have these in my tank. Do you have any idea what they are? Are they good slugs/flatworms? Or bad slugs/flatworms? Should I just forget my dream of giving some lucky fish the feast of their lives and clean the tank out before I introduce any fish into it? <Those are small leeches, annelid subclass Hirudinea. Now, the vast majority of leeches are predators on invertebrates. Very, very few are bloodsuckers. But obviously those that are can be very damaging to fish, particularly very small fish. Identifying leeches to species level is difficult, and definitely a job for your friendly neighbourhood freshwater ecologist or parasitologist. Identification beyond subclass level is below me, I'm afraid! In the meantime though, don't kill it out of hand. Leeches are lovely animals, and if you can encourage it to go swimming you will be treated to one of the most beautiful little spectacles in the animal kingdom. They also have a very cute "inchworm" mode of walking. The sucker at the front (blunt end) is armed with teeth with which it catches its prey, and most species suck up the "juices" of whatever they've caught either directly or through a neat little stylet. You can also see the digestive system quite nicely in your photo, too. All in all, charming, if weird, animals.> Thanks! <No problem.> Take care, <Will certainly try! Neale> Mary.

Thin Clear - Whitish Worms - Nematodes/Planaria 7/21/07 Dear WWM, <Andrea with you tonight, Jean> Today I had noticed a several thin, clear, whitish worms crawling up the side walls of my 6.6 gallon freshwater aquarium tank (visible by a bright aquarium light). <Planarians or nematodes, most likely. Sign of overfeeding. Cut back to once every other day, only what your fish can eat in about two minutes. Net out any uneaten food remaining.> Once a week, I maintain my tank by vacuuming the gravel and performing a 20 percent water change. I always premixed my water with aquarium salt and stress coat, a night or two before I perform my tank maintenance. <Fantastic regimen. You can dump the salt, it is worthless as a tonic, and can actually harm some fish. I prefer Prime as a water conditioner. Less used per water change, and no additives other than what is needed for neutralizing chloramines/chlorine from tap water. Prime is a great product. I highly suggest it.> Recently, I treated my Betta with Jungle Parasite Clear because he had contracted a parasite. This parasite problem was due to me feeding him live black worms, which I stopped feeding him. <Shame. I bet he loved the live feeders. Don't discount them in the future as a treat. Bettas love them. Perhaps another live feeder provider?> My question is, can those thin, clear, whitish worms crawling up the side walls of my tank be a parasite? <Not likely.> Is this dangerous to my Betta? <He will likely eat them. Not a danger.> If so, how can I get rid of them? <Reduce feedings, water changes, deep gravel vacuum.> Treat my tank with Jungle Parasite Clear again? <No, unless the fish is sick.> Please give advice. Thanks again for all your help; your site is the greatest. <Anytime, we are here to help!> Jean

What are these tiny brown worms in my 10 gallon aquarium? 7/21/07 Hi my name is Donna, I've had my 10 gallon fish tanks for about 3 yrs I was changing the filter tonight and I noticed a couple of little brown looking worms that are located on some of my artificial plants that I let float in the top of my tank for my baby guppies to hide in are they dangerous to my guppies and Platies ? what are they ? and how do get rid of them ? should I completely break down my tank I was hoping to be able to wait a couple of weeks before breaking down my tanks until my new mobile home is set up so could put all my fish in my 55 gallon will my fish be ok till then ? <Hello Donna. These worms are almost certainly planarians. These are usually flat and liver-coloured, and around 5 mm long. The slide along things rather than wriggle. Sometimes they slide along the surface of the water. They are harmless, although they will eat fish eggs and are a nuisance in tanks where egg-laying fish are being bred (been there, done that!). Otherwise all they do is eat microscopic organisms and detritus. In a tank with guppies and other livebearers they are harmless. Besides, getting rid of them is difficult and only worthwhile if they cause a problem. Some fish will eat them (paradise fish are famous for this). They're interesting animals and worth reading up on when you get a chance. Cheers, Neale>

Red Worm ID (Royal Plec)... Insect 11/19/07 I've had a 3 1/2" Olive Royal Plec alone in quarantine for 10 days or so. I dewormed with Praziquantel last week at the recommend dosage (76 mg/10 g) as I know they're wild caught and don't want to pass anything onto my own fish. He went into a 20 gal tank with new aged water and a fully cycled Penguin 280 bio-wheel filter from another tank. I did his 25% water change today (after leaving the Praziquantel in 5 days) and found these live red worms (pic attached) in the water I syphoned off the bottom of the tank. Pretty wiggly and entertaining under the microscope but I can't figure out what they are via the FAQ's. If they weren't alive I'd have thought they were frozen bloodworms. I'm hoping it's a harmless worm that can be treated as the Plec is eventually going in with my much loved Severum. I promise not to bother you anymore, but maybe the picture will help others. Mitzi <Looks like a chironomid larva (a.k.a. midge larva or bloodworm) to me. Probably got in with some live food. Usually get eaten by fish, so not common in aquaria. But if this tank was empty for a while, then it's possible a midge laid some eggs there. In any case, harmless. Cheers, Neale.>

Re: Red Worm ID (Royal Plec) 11/19/07 Thanks, Neale. I feel stupid then but thankfully that's good news. I never feed live food, but the driftwood in his tank had been soaking for a month in a large kiddie pool outside. I rinsed it off real well but I bet that's where the bloodworms came from. (The tank had been empty and stored before he went in it). What a relief! Mitzi <Mitzi, Glad we have a happy ending here! Cheers, Neale.>

Worms in fresh water aquarium 11/29/07 Hi WWM My sister has a fresh water Aquarium which she just cleaned out on the weekend, and a few days later we have noticed these worm like creatures in the filter tubes no where else but in them. They have small legs and are hatching out of these things that look like cocoons and if you look carefully at them they have small mouths. There very disturbing to look at and gross us out. There's so many of them please help! Jessica <Hello Jessica. Without a photo its impossible to say what they are. But given they have obvious limbs and mouthparts, one must assume they are some sort of insect. Aquatic insects vary in their danger to aquarium fish: most are simply fish-food, but a few, particularly dragonfly (Odonata) and beetle (Coleoptera) larvae, can turn the tables and will catch and eat small fish. If you can send a picture, we can try and identify your visitors with a bit more precision. Cheers, Neale.>

Is this a worm? FW Polychaete of size! 2/10/08 Hi there, I have a freshwater tropical tank with 13 guppies, 3 fry, 2 Corydoras and 2 Bristlenose in an 80 litre tank (2ft wide, 2ft high, 1 ft from front to back). It is planted with java fern and one wisp of wisteria. There are also small snails that have arrived with earlier plants. I do a 25% water change each fortnight and the water parameters stay fine, though the PH runs a little on the high side. The adult guppies are from fry dropped by an earlier batch of fish that were lost to (I think) columnaris. One or two earlier males also went from dropsy. I suspected parasitic problems last October, the fish were a bit listless and had pale faeces. There were a few casualties and I treated with Para-ex (20 mg Trichlorphon). This sadly killed our original Bristlenose and our baby Corydoras but the guppies have gone on well aside from the occasional undiagnosed fatality. One month ago I bought 2 more Bristlenose to replace the original and help keep the tank clean (we were getting increased algal growth). This has been the only introduction to the tank from outside for approx. 6 months. Yesterday, while doing the water change, I was disturbing the gravel to syphon out waste matter when I unearthed a wriggling worm type creature. I attach a photo. It is about 4 cm long and wriggles in the way of a snake. It has a multitude or what look like legs along the length of its body. There are 2 discernible eyes under magnification. What is it? Is it a danger to the tank? How do I treat/cope with it? A suggestion was made that I get a couple of loaches to hopefully eat it (and its offspring?) as a 'natural' form of management (rather than treat with Para ex again and have to try to manage the health of the Bristlenose) but I am concerned that they are a more aggressive fish than my current inhabitants. Or is it not a parasite at all? I am concerned for the state of my tank, particularly given the size of this creature and my assumption that it's not likely to be the only one. Any advice or info would be gratefully received. Sharon <What you have there is a freshwater Polychaete. It is no risk to your fish and will not be carrying parasites. So the appearance of this worm and the death of your fishes are entirely unrelated. Freshwater Polychaetes are comparatively uncommon; they are overwhelmingly a marine and brackish-water group in terms of success and diversity. I'm guessing yours is a member of the family Namanereidinae, perhaps one of the many species of Namalycastis. Regardless, the freshwater species are not predatory (unlike some of the larger marine species) and feed primarily on decaying vegetation and rotting wood. They may also be taking micro-organisms of various types. I suppose they might also eat fish eggs, but then so will snails and fish. Actually rather a lovely find, and you may decide to set up a special aquarium just for these worms -- they are not at all commonly seen in fish tanks and would be well worth observing in more detail. I'm really quite jealous! Cheers, Neale.>

Re. Is this a worm? FW Polychaete of size! 2-14-08 Hi Neale, <Sharon,> Thank you very much for your response and info about my newly discovered tank resident. I had separated it out as a precaution but have returned it to the community on your advice. A shy chap, I don't know if we'll see it again! At 4 cm, is this a large or small specimen and what do we expect now? <About the going rate. I'd be surprised if he got very much larger.> Does it have special needs I should be aware of? <If a true freshwater species, then likely perfectly happy where he is.> Is it likely to be the only one? <I've never see these worms in tanks as accidents, so if you have one at all, that's pretty amazing. To have more than one would be outrageous fortune! They don't breed in aquaria, so far as I know.> By the way, I don't know if you send a reply email to the questions as well as posting, but I originally sent the question from my husband's email (as it is the mail default on the computer). If you replied, he has trashed it, I guess, not recognising the sender. Sorry! I send from my mail now. <Questions get returned to the original e-mail PLUS a copy is posted to the WWM web site.> Thank you again for your help. I am much relieved! Sharon <Enjoy your new pet! If you have a biology interest, read up on Polychaete Worms, and you'll find out that freshwater examples are very rare. What you have is a really nice beastie to treasure. They do get sold on eBay and the like, I'm told, but have yet to see them in the UK. Cheers, Neale.>

A very nice pic. RMF

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