the Flatworms that are
Related Articles: Snails and
Freshwater Aquariums by Bob Fenner, In vertebrates for
Freshwater Aquariums by Neale Monks, Assassin Snails and
Sulawesi Elephant Snails. Keeping Clea and Tylomelania in the
Aquarium by Neale Monks, Fresh
and Brackish Water Nerites by Neale Monks,
Related FAQs: Freshwater Snails 1, Freshwater Snails 2, & FAQs on:
Freshwater Snail Identification,
Freshwater Snail Behavior,
Freshwater Snail Compatibility,
Freshwater Snail Selection,
Freshwater Snail Systems,
Freshwater Snail Feeding,
Freshwater Snail Disease,
Freshwater Snail Reproduction,
Snails by Species: Mystery Snails, Malaysian/Trumpet
Unknown roundworm in aquarium 10/2/18
I saw this worm yesterday in my aquarium. Could you please help me
identify it and whether or not I should get it out of my tank?
<Umm; nothing attached. No photo here>
It's currently in a 29 gallon planted tank with dirt (from a bag) and
the tank is about a year old. The most recent addition in the tank was a
pond plant. Could it have come in that way?
<Oh yes; roundworms, nematodes are VERY common; almost all are
innocuous; not harmful>
It doesn't look segmented and seems to have a suction on one end
(the back end). The back end doesn't look like an earthworm where it's
tapered, but looks kind of blunt, like it was cut. I haven't
seen it burrow into the substrate or crawl up the glass like other
worms. It's brown and looks
"solid" rather than clear.
<Oh... this reads more like a leech, Hirudinean, rather than a
roundworm; which are by and large smooth, tapered at both ends, light
I've uploaded a video I took earlier today.
<Unfortunately this video isn't playing for me>
Hopefully the video is clear enough. It moves pretty quickly, but it's
not shy. I could probably get another video or picture if you need it.
<Do please send the image, video link along>
Please let me know if you need any additional information.
<I'd be removing this worm>
<Thank you for sharing. Bob Fenner>
Re: Unknown roundworm in aquarium 10/3/18
Thanks for getting back to me so quickly.
Sorry for the broken link. The video was uploaded as private, rather
Here's the new link: https://youtu.be/wd_PdDDcxLA
Please let me know if there are any problems with it.
<Oh yes; this is a Leech (yeah, yuck); possibly parasitic on your
livestock. Remove it (w/ extreme prejudice)>
Re: Unknown roundworm in aquarium 10/3/18
Thank you for the id.
So, if I'm looking at it correctly, the leech is moving backwards? It
searches with the tapered end and uses the blunt end as an anchor.
<Hirudineans have "haptors" on both ends, and can move backwards and
forwards using them and extending their bodies>
Thank you again.
<Certainly welcome. B>
Freshwater black leeches in tank
They must have come in on plants. I read that getting rid of them is
impossible. Have been removing gravel, but eggs will remain?
<Hard to say.>
Never knew such a thing existed. Identification is definite: inch long
extended, collapse to about half inch, black, hang on with mouth end,
can wiggle through water but mostly hide.
<Do bear in mind many of the common leeches you find in clean freshwater
are carnivores on small invertebrates, and pose no risk to fish. So
there's no need to be completely paranoid about them.>
What do eggs look like?
<Varied; small, often nondescript; do see Google Images, re:>
Will my weather loach eat them, especially with less gravel for them to
<Yes, but I wouldn't completely rely on it to get rid of all of them.>
Any other fish eat them?
<Most fish that eat worms will eat leeches if they can.>
Also have mystery snails....will they be contaminated by them?
Any chemical solution that won't hurt snails, loach, tetra in tank?
<Anti-helminthic medications should work, such as PraziPro, but these
may harm invertebrates such as snails and shrimps. I would remove the
Mystery Snails to another container for a few days while using such
I really hate these creeps. Have gotten evil pleasure washing gravel in
small batches in very hot water and watching dead leeches flow away.
<Leeches are important predators on genuinely annoying organisms such as
mosquito larvae, with very few species actually posing a threat to
humans, and even then, they're more of a nuisance than a health risk.
Modern medicine doesn't use them as much as in medieval times, but they
still have value in reducing certain types of swellings and
inflammations better than anything else. So while few people want them
in their fish tanks or ponds, they do deserve a bit of respect, even
But I know this is only reducing population. Does this harm eggs?
<Anthelminthics should handle worms and their eggs.>
<Cheers, N Monks.>
Re: Freshwater black leeches in tank 7/9/18
You are awesome.
<Nice to know!>
Thank you so much.
Yes, I am aware they can be very helpful in micro surgery cases. But I
have watched/loved African Queen movie...
<Ah, great film.>
Again, thank you so much. Google actually confusing, could find no
photos of eggs, much non-info.
<Oh? Well, simple small off-white to grey spheres, maybe 1 mm across.
Different for different species.>
Yours the best.
<Glad to help, Neale.>
The Fate of my Leeches 10/10/11
First I wish to say greetings to you from both my husband and me. We
have both looked for answers to our questions on WWM over the
<Thanks for your kind words.>
Here is some background information: I have a 16 gal bow-front tank
which has been set up for a few years. It contains cherry shrimp, class
N Endler's, Hara jerdoni, Scarlet Badis, Malaysian Trumpet snails,
and Tanichthys micagemmae. This tank also is thickly planted with
various Cryptocorynes, Bolbitis heudelotii, and Windelov java fern (the
latter 2 attached to African Mopani Root Wood). For filtration I use an
Eheim HOB filter. I also use an air pump with airstone to keep oxygen
levels up at night due to all the plants. I recently added a moss ball.
As everything else has been in the tank at least a year, I am guessing
that this may have been the culprit.
<Perhaps. Moss Balls -- if you mean those Cladophora colonies -- are
coldwater algae, and as such, may be cultivated outdoors or in ponds.
As such, they may bring in all sorts of pond life. They don't do
particularly well in tropical conditions, and without constant rolling
around like they get in the wild, eventually fall apart into some sort
of mat or lump.>
Last month, I noticed a light gray "worm" of about 3"
length and perhaps 1/4 - 3/8" wide swimming like a snake in the
tank when the lights first came on by timer. It rapidly headed for the
substrate and buried itself.
When I feed in the mornings (but not in the evenings), I occasionally
see a portion of this "worm" sticking out and attempting to
catch bits of food.
<Sounds like a leech!>
I feed New Life Spectrum small fish formula 0.5mm size, Fluval Shrimp
Granules, New Life Spectrum optimum freshwater flakes, and live Daphnia
(species unknown -- local culture I have kept going indoors for a
couple of years). I have never seen any type of worm in my Daphnia
Last time I vacuumed the gravel, two of these "worms" were
left in the bucket and were attached at both ends to the plastic bottom
of the bucket.
This is what made me pretty sure I had leeches. I attempted to take a
picture then, but as my camera is of poor quality, the results were
nothing more than a gray blur.
Now, here is the question: I find the leeches are pretty awesome. My
fish all appear healthy and are eating well. My plants look fine. The
shrimp are still reproducing. I actually enjoy watching these leeches
move around in the tank (when I am lucky enough to see them swim) and I
enjoy watching them try to catch bits of food. My husband is of the
"EWW it's a leech!"
school and advises a full tear down of this tank to remove the
offending leeches. We have 7 tanks total between us. This tank has its
own gravel vac and siphon tubing and its own nets. We use one set of 5
gallon buckets for dirty water and 5 gallon drinking water containers
for clean water. I don't see much chance of contaminating the other
tanks with my leeches, but this is his worry. He is concerned that I
will put leeches in our 125 gal Tropheus moorii Moliro Red/ Eretmodus
cyanostictus Kapampa tank. My only real concern is for my Hara cat and
my Badis. They both love to eat tiny live things and I am somewhat
concerned that they could become ill from eating baby leeches.
<Most leeches are in fact free-living and feed on invertebrates. So
things like bloodworms would definitely be on the menu! They may even
scavenge to some degree. Some are blood-sucking on fish, but these tend
to leave obvious wounds, often with a three-tooth bite distinctive to
this group of animals.>
We have agreed that we will post this issue to WWM and proceed as
Both of us respect your opinion on such matters.
<Without a positive ID it's hard to be sure. If this was me,
I'd perhaps experiment first. Put them in a breeding net, and see
if they eat wet-frozen bloodworms or krill. If they do, and seem to be
free-living rather than parasitic, doing well for a few weeks under
such conditions, I'd then maybe try them out in a tank with fish
too large to be damaged.
But I'd keep a very close eye open for odd bite marks. Hope this
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 dÃ©colletÃ© 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
can't/don't live long w/o hosts. Do yours show segmentation,
If they are harmful how do I eliminate them?
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
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.