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FAQs on Aquatic Insects and Freshwater Aquariums: Identification

Related Articles: Invertebrates in Freshwater Aquariums, Invertebrates for Freshwater Aquariums by Neale Monks,

FAQs on Aquatic Insects:  Aquatic Insects 1, Aquatic Insects 2, Aquatic Insects 3, Aquatic Insects 4, Aquatic Insect Identification, Aquatic Insect Control
FAQs on Aquatic Insects by Group: Beetles, Dragonflies, Flies in General (Caddis, Gnats, Midges...), Freshwater Mites, Mosquitos/Mozzies and much more!

& FW Invert.s 1, FW Invert.s 2, Hydra, Worms, Crustaceans,
Shrimps, Crayfishes, W and Brackish Crabs, Terrestrial Hermit Crabs,

Worms in my tub!      5/3/17
Hello! Can you please tell me what kind of worms these are?
<Video Link HERE>
I found them in my bathtub after giving the kids a bath! We live in northwest Indiana if that helps any.
<These look like insect larvae; likely hatched from "flies" getting into the house, some bit of water left in the tub... no worries. Bob Fenner> 

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 Fluorish 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...

<12 megs of blurry pix>... Free contaminants w/ live plants  bonus!      9/8/15
Somebody gave me this plant to put in my tank,
<Should have quarantined/isolated; treated prophylactically...>
it has been in there for about a week or two, now there are these bugs, I have one fantail goldfish in my tank, I don't know what they are or what to do if anything, please help, thank you, Lisa
<Do these look summat like Coleopterans to you? See (READ on) WWM re. Bob Fenner>


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>

Strange worms in tubes and algae       3/13/15
I have a newly planted freshwater aquarium with no fish. I have a few Amazon swords, crypts, and Anubias plants. I have 2 t5 fluorescent grow lights. My planted tanks has some kind of dark green algae with squiggly lines and with some kind of worms. The worms are growing in some kind of single tube.
<Indeed! Sessile chironomid larvae or similar. Also an Hydra visible in one photo, the branched, off-white tree-like organism.>
The worms poke their heads out of tube for a few seconds and then go back in the tube and hide.
I can't find anything like them on the internet and was hoping you might be able to tell me what they are and if I should get rid of them and is it safe to put fish in the tank with them?
<Harmless filter-feeders; fish food. The hydra is a bit more of a risk in a breeding tank (will catch, eat tiny fry).>
Here is a couple of pictures. Thanks in advance for any help you can provide. Sincerely, Robert.
<Most welcome. Neale.>

very nice pic.

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>

Could you all please I.D.      1/1/15
Any clue? I've asked around, yet nobody seems to know.
<Mmm; would like a bigger, better resolved pic... My initial guess is that this is a juvenile Tunicate, a larval Ascidian of some kind/species.
Bob Fenner>

Re: Could you all please I.D.     1/2/15
This is the best I have
<Video clip>
 I had gotten rid of him, I didn't want him to harm my tank.
Thanks for getting back with me bob fenner
<My guess is still on the Thaliacean. BobF>
Inputs for Bob (Re: Could you all please ID dated 1/1/2015)   1/3/15

To my Kumpadre Bob,
<Hey Rix!>
Hi! I hope you and the crew had a great time during the holidays. I'd like to chime in on the erstwhile unidentified organism in the letter dated 1/1/2015. No info was given regarding the habitat, but if it was collected in freshwater, it might be a rat-tailed maggot.
<Just looked up; neat!>

I had fun collecting these in anoxic creeks during my younger years in Manila (gosh the memories haha). Hope this info helps. Thanks for all the help you and the crew have been providing all these years, and wishing you all the best for 2015.
Rix Pavia
<Mabuhay mi pare jo! Bob Fenner>

Weird Things in my Tank     11/6/14
Hello, my name is Brooke. I'm writing in regards to these strange creatures
I found in my boyfriend's fish tank. He has a 29 gallon tank that was purchased on September 27th. He currently has 3 Gold Danios and a couple snails. He's waiting for the tank to cycle before adding other fish. The PH is about 7.2. The ammonia fluctuates between 0 and 0.25, the Nitrites are 0 and the Nitrates are at 40. He's new to the hobby, but has done everything according to what the people at our local fish store have recommended. He keeps the tank at 76 degrees. He has an Aquaclear 30 filter. He has live plants that were purchased at the time of the tank, before the fish. He has, I believe, Fluorite Black substrate mixed with a little black gravel.
We do weekly 10% water changes. During the water change, he suctions the substrate as well as he can without digging up plants. I'm not sure if all of this is useful to you in helping to ID these creatures, but figured it would be better to include it, just in case. I noticed the creatures about a week ago. They looked like small bits of root coming off some of the plants that have been floating at the top of the water. The creatures were green in color, small, and long. After closer inspection, I saw that there were also some that were a little larger and brown. I did some research (days of pouring over Google as well as your site) and couldn't find anything other than maybe a Damselfly Nymph, but still felt like it was unlikely. I decided to watch and see what happened. As they got larger, they started to look like they had little bug or shrimp bodies sticking out of the long, skinny, brown "shell," and I could see a "vein" pumping through the "shell." They also look like they have a long piece of plant root attached to their top sides. They don't seem to have a preference as to which portion of the tank they are in, as long as they are on something.
I've seen them on plants at the top, walking on the walls, and walking along on the bottom of the tank. Although, they do seem to like being on the plants the most. I tried to get a few pictures of them, though it's
hard as the biggest are only about an inch in length. I'm including a picture of a smaller one as well as a close up of a larger one from the top and a larger one from the side. My main questions are: What are they? Are they safe to keep? If not, what should I do? If they are, is there  anything I need to know about their care? I've found them quite interesting to watch, so I'm hoping they are keepers. Thank you so much!
<The photos aren't sharp, so can't be sure. But are these Caddisfly Larvae or something similar? That's what they look like to me. They're hugely diverse, including some species that eat algae, some that feed on particles of organic matter, some that capture small invertebrates such as other insect larvae. I can't think of any that eat fish, and they're so small none should be a threat to anything bigger than, say, fish fry anyway. So you might want to observe this beast a while longer. Look up Trichoptera in your local area and see if any match the animal you have here. Cheers, Neale.>

Re: Weird Things in my Tank     11/6/14
Thank you so much! It looks like that is exactly what we have. I suppose we'll watch them, and once they have emerged from the water, we'll catch them and let them go outside. They're really quite fascinating! It's hard to believe they've built their cases out of stuff they've found in the tank!
I really appreciate all your help as well as your quick reply!

FW parasite ID     8/18/13
Good morning
 <And you>
I wondered if you could help with identifying the attached...
 I found 8 of them on the bottom of my quarantine tank after treating a sick platy with an anti-parasite medication (liquid Praziquantel 'Prazi Pro') . As far as I know they came from inside the poor fish.
 <Mmm; appear to be chitinous in this pic... external, or gill cavity (which is also ext.)...>>

The heads are dark and visible to the naked eye. About 0.3mm across. The bodies had largely disintegrated before I got them but looked to have been maybe a cm or so long and worm-like...
<Hmmm; please do send along an image of a whole specimen if you can>

without the dark cuticle (?) visible on the head part. I did see some other structures - a node with fine hooks or hairs (bursa? couldn't tell which part it had been attached to) and the structure coming from the inside of the head shown on the doc. file. 
 Hunting around on the web the closest I can find is some kind of hookworm ... what do you think? The teeth and claw structures are really distinctive but I couldn't find a picture of anything quite like these anywhere...
I'd like to know what they are and whether my main tank is likely to be swarming with eggs and larvae just waiting to latch onto one of my other fish and whether there is any point in re-treating my sick fish with the Prazi Pro - she is still very sick-looking and not eating. (It is 7 days since I first quarantined and treated her)
<If they are worms, the Prazi has likely eliminated them; if crustaceans; you'll need to treat w/ another compound. See WWM re such for freshwater fishes.>
Any help/info would be appreciated!
<The head, mouth parts, are reminiscent of Ergasilus, some other copepods... perhaps... Bob Fenner> 

Re: unknown parasite, FW...      8/18/13
Thanks for the quick response! Had a look at Ergasilus spp on the web - but nowhere seems to mention they have 'teeth' - which are very distinctive in the species I have and I think would be commented upon somewhere...
<Mmm, yes>
I have make the attached composite photos of the 2 specimens I have of bodies ('body 2' has two versions - a light and dark)... I am afraid both specimens are in pretty bad shape but I had another good look under the microscope and can't see any obvious structures like legs or chitin plates etc... so don't know if these help much! I am also not sure if they are complete or the tail end has broken off - looks broken to me so there could be missing parts.
<... no apparent legs? Quite common in internal parasites; and of course worms lack them... But do have eyes; and these too tend to be absent, or greatly reduced... These appear to be segmented... and still arthropods...
Did you actually see them being evacuated from the fish's vent? Am leaning toward (guessing) aquatic insect larvae... non-parasitic; though can be piscivorous... Do put the string "freshwater aquatic insect larvae" in your search tool and take a long look/see at images... do any of these bear close resemblance to what you have here?>
Sorry about the quality - I am just holding my camera and taking shots down the microscope tube.
<Good work; better than I could do. BobF>

Re: unknown parasite     8/18/13
Oh - that's an idea! I'll send the photos to a friend who is an aquatic invertebrate person... though I have to say I still think they must be parasitic. I scooped the sick fish out of the aquarium in a small container to transfer her to the quarantine tank and  I think I would have noticed if these guys were with her. But maybe not! Perhaps there is something else completely different wrong with the fish...
<... do look at the system this fish was hauled from... At the surface especially. B> 
Re: unknown parasite     8/18/13

I agree - the mouthparts do look like those of an insect....
Any suggestions as what to do with my sick fish? Any other treatment (if it 's not an internal parasite) you can suggest?
<As you were first directed.>
Symptoms are - very thin, lethargic, not eating or if eats - spits food out, has been like this for at least last 2 weeks (was away on vacation before so not sure how she was...), other fish in original tank all fat and bright, can't see anything obvious on her externally....

Re: unknown parasite     8/20/13
FYI Identified the mystery 'parasite'
 It's a midge larva!

Not a parasite at all but residue from feeding bloodworms... must have been in the water the fish was transferred in (from the main tank) or from her gut and pooped out once in the quarantine tank...
 <Ah yes; as I had guessed>
Back to the drawing board for my diagnosis!
<No worries; not harmful. Bob Fenner>

Is this a bloodworm?     4/26/13
I've recently (last few months) started building a freshwater tank - the last one I had was taken down due to moving to FL, and the fish given to a LFS (I haven't gotten any new fish yet).  I was kayaking last week and noticed some *Egeria *type plants*,* and grabbed some to start a planted tank.  I kept them out of the tank until today to make sure there weren't any snail hitchhikers, and today I put them in my tank.  As I was cleaning up and about to throw out some plant debris, I noticed little tiny red worm-like things flailing around in the plant matter on my kitchen counter.
After freaking out a bit, I Google searched to see if I could figure out what they are - they are probably in the tank since I didn't notice them until *after* most of the plants went in the tank.  I'm assuming they are bloodworms, but could you double check my identification?
<Could be a Chironomid... an insect larval stage of some sort>
  I'd hate to have any eventual fish I get subjected to a parasite I pulled out of a river.
Thank you!
<Welcome. There's always a chance of introducing trouble/s w/ such wild collecting... Better to run all new material through a few weeks of isolation/quarantine, before introduction to your main/display system. Bob Fenner>

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 Yellow Bugs 2/6/12
I just cleaned my tank today and noticed these tiny speckles above the water line. On closer inspection they were crawling. They are extremely small yellow bugs, no bigger than a pencil dot.
I looked through your posts and found one question about something similar. I have seen them floating on the water as well, but mostly on the side of the tank. I can see antennae and six legs if I strain my eyes.
I too have a fresh water and live planted aquarium, 20 gallons.
However I believe I know the culprit. I've found these brown bugs in the same room as my tank, adult size is about a 1/2 inch. I don't know the proper name, but I was told they're called Stink Bugs, because of the scent they emit when in danger or crushed. I found one hanging out on my filter while I was cleaning. I've found others there before, attracted to the light and heat, but never saw the little yellow guys before. They are however very similar with six legs and antennae. Also the same body shape.
In the photo I've sent you (I apologize for the lack of detail), you can see tiny little dots just left of center. Those are the little yellow bugs. I don't have a picture of the adult stink bug.
I just thought you guys might want an idea of what these tiny bugs might be. Please let me know if there's anything I can do to get rid of them. I've been using a paper towel and just wiping them out.
Thanks for all the great feedback you've given!
<And thanks for the kind words. Anyhow, these are harmless tiny insects, collembolans, mites, silverfish'¦ that sort of thing. Quite normal. Nothing to worry about. The fish don't seem to eat them, but conversely, they don't seem to damage the fish or plants either. They're mostly feeding on organic material that collects in warm, humid places like fish tanks. Cheers, Neale.>

Freshwater insect larvae ID 6/26/09Crew,
I mostly tore down my QT tank before going on a work trip 2 weeks ago.
While I was gone there was gravel enough to cover the bottom and water to just cover the gravel (maybe 1cm). I was cleaning the tank today by adding hot tap water and I noticed what I assume are insect larvae. Sorry the pics are out of focus. The long, gray UFO (unidentified freshwater object)
is about 1.5 cm actual length. The other 2 are about .5 cm.
<It's the larva of a dipteran of some sort. Midge, mosquito... something like that.>
No matter what, I plan on having all these things cleared out of the aquarium before the wife sees them. She hates anything wriggly!
<They're fish food. Not a problem.>
Thanks for any help.
<Cheers, Neale.>

Weird Creature, Help! 6-15-2009
I have sent this photo to about 10 sites and not one has responded, do you guys know what this is?
<It's an aquatic larval insect of some sort... need to see details of the head to get close as the Order>
I live in Castle Rock, CO at about 6300 feet, these things are flourishing in my little 3' x 2.5' pond; no circulation, only duckweed, 1 water hibiscus and 1 water hyacinth.
This is a photo of one; it's in a jar, I used the macro feature on my camera; they are from needle pin dots to 3cm. Obviously a crustacean (from the tail/abdomen which shows 6 sections) but the body seems upside-down with feet on the top a large eye?
Any input would be greatly appreciated.
<More pix please. Bob Fenner>

Spiders in my silver dollar tank 5/8/2009
Hi guys,
I have Googled till I'm cross-eyed, but still can't find any advice on a creature I've found in my tank when vacuuming.
It looks like a silver grey spider, body about 5 mm long, 3 mm wide, 6 legs, and is quite active. The total leg span would be about 1.5cm.
<Well, if it has six legs, it's an insect. My guess would be a Damselfly larva; these are quite commonly seen in fish tanks, coming in with aquatic plants and portions of live food. They are predatory, but beyond fish fry, it's hard to imagine them causing real harm.>
It was cleaning the muck off its feet in the bottom of the bucket and is quite cute. I'm reluctant to kill it or to put it back incase it's a parasite and my harm my large silver dollars.
<Damsel- and Dragonfly larvae are indeed fascinating animals, and easy enough to rear in floating breeding traps. They can be hand-fed live or (wet) frozen bloodworms using forceps.>
I know they're not in the right tank, I have a large bio-orb, which is actually difficult to clean as the filter sits in the bottom of the orb and is quite small, but they grew so quickly, I'll need to buy another tank.
<I'll say! Just as an aside, BiOrb tanks may look good, but in terms of fishkeeping, they're very poor value for a whole host of reasons. Stick to traditional long, rectangular shapes. Avoid anything tall, round, or otherwise odd in shape.>
My local aquarium isn't much assistance, they couldn't identify the leech, red thread worms, or little white flea like creatures.
Still, thanks for your advice.
<Happy to help.>
I'm loving owning fish and there's so much to learn. I now have 5 tanks!
Started from one, but fish grew, bred, had personality issues.... I'd better learn quickly.
<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.>

Strange Creatures in FW tank 9/20/08
Hi people
On performing a water change earlier today, i noticed a couple of odd creatures which came from within the gravel of my goldfish tank. Any idea whether these be friend or foe. Actual size is around 12mm (½?) in length...
Thanks in advance J
<Hello! This URL asks for a log-in and password. How about just sending a small (max, 500 k) attachment? That's what most folks do, and we thank them for it. In the meantime, most small bugs and worms in fish tanks are harmless. Cheers, Neale.>

Strange Creatures in FW tank
Hi Neale
On performing a water change earlier today, i noticed a couple of odd creatures which came from within the gravel of my goldfish tank. Any idea whether these be friend or foe. Actual size is around 12mm (½?) in length...
<Hi Brad. This is, I believe, a Damselfly larvae; looks like a Dragonfly nymph, but the give-away is the "tail" made from three filaments. Dragonfly larvae are bigger, have more robust jaws, and a stubby "tail". Damselfly nymphs are predatory, but only sufficiently large to take small fish, perhaps livebearer fry. Otherwise they're fish food! Quite fun to rear yourself, they can be hand fed bloodworms with forceps, and it's rather fun to watch their bizarre mouths anatomy in action. Dragonfly larvae are much more dangerous to fish, some varieties being anything up to around 8 cm/3" long (at least here in England) and more than capable of eating things like minnows. In any case, almost certainly came in with live plants that were grown outdoors, though possibly in batches of things like Daphnia. Does rather stretch the imagination to assume either a Damselfly or Dragonfly flew into your home and laid its eggs there, but it's possible I suppose! Cheers, Neale.>

Re: Strange Creatures in FW tank 9/21/08
Hi Neale
Thank you for the response. Since I only have large-ish goldfish in the tank, looks like they will not be a problem. I do buy live plants for my fish to snack on, so I guess that was the ticket in for the larvae.
Thanks again
Brad :)
<Hi Brad. Those Damselfly larvae should cause no harm to your Goldfish; in fact I'm surprised they haven't been eaten yet! 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>

Please Help Get Rid of my Flies!!!!(My last resort) 2/10/08 Hello I have scoured The net looking for a question and my LFS recommended this site, so here we go. First of I am running a 65 gallon fresh water tank. Two HOB Bio Wheels. Heater etc. . My temperature is usually aprox 77/78 deg. There are two prismatic lens covers on my aquarium. The transparent kind you see under fluorescents in stores/ schools. With aprox 6 inch square of open space on each one. There are 4 Platys 1 Sail Fin Pleco (2.5-3inc) <A what...?> and 12 harlequin Rasboras. The nature of my problem are tiny green flies. They first appeared on the surface of my water as see threw shells. Within a day they "fly away" and get stuck under my lid. My LFS said they could not be actually flies on the water surface and must be a aquarium pest. Where as since then, I have definably seen them fly away. When they Grow wings and get bigger aprox 1/2 mm they change into a fluorescent green. They are located around my filters , and are reproducing fast. Some one suggested they are coming from my filter pads. Whereas they are under water. Dose that make sense. The only new addition to the tank was a batch of aquarium moss. Which has since been removed. Where as the flies still reproduce and cause me a large head ache. I clean the inside of the lids every two days now and there are between 30 and 100 every time. They are so small that when on the water surface my fish cant see them as such cant eat them either. That is all I know. Presently I am syphoning water from the surface at my water changes to attempt to rid them of my tank. Like I said removed all new additions and am maintaining a regular water change schedule 10/15% every 2/3 days. Any help would be great. Ps have no photos where as I can try and resend the email towards the end of the week If need be with new photos. Just email me and ask thank you ever so much. You are my last resort. <Well, not precisely sure what these "flies" are, but I also doubt they are actually true flies, i.e., Diptera. Fish usually DEVOUR dipteran larvae, and there's not much chance a population of mosquitoes or some other (semi-) aquatic fly could actually maintain a population in a fish tank. It is much more likely you have thrips or some other insect that walks on the surface of the water. Now, there are two key things to known. Firstly, they don't do any harm. Most freshwater tanks have played host to these at some point. They don't carry diseases and they don't harm your fish. The second thing is that they don't break the laws of physics: if they're multiplying, its because they're finding something to eat, most likely decaying fish food. You don't see these insects in clean tanks with strong water currents. You see them in tanks with variable levels of cleanliness and filters insufficient for the tank/population of fish. Even adjusting the filters so that there is more water circulation will make a difference. In any case, these insects migrate into the tank from the rest of the house. They'll come from other warm, moist places. You can't exterminate them so either make the tank less attractive for them, or simply ignore them. Cheers, Neale.>

Red Worm ID (Royal Plec) 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.>

Re: Alaskan Isopod! One Id down, now on to the Water Beetle! 11/16/07 <Hi Jack!> Thanks for identifying the isopod for us. <You're very welcome!> It is known locally by Inupiat Eskimos as a "toe biter". I doubted they had the ability to bite toes, but perhaps they actually do. <I would imagine so. Those isopods can get relatively large - around 3'. I sure wouldn't want one grabbing hold of my toe!> We have a large(3 cm) water beetle living in the same aquarium as our specimens of Saduria entomon. It preyed upon our snails and is now preying upon the S. entomon. <Ah yes, I see. The predator becomes the prey!> I have had trouble identifying it and hope that you can help. <Hope so> It breathes with head down and stores a large air bubble in its tail region. <Typical> It is quite buoyant and uses a lot of energy to dive. <I've seen videos of this. It looks extremely awkward, and reminds me of trying to see how deep/far I could swim with an inner tube around me as a kid! LOL I didn't do as well as these insects, and I'm very thankful that there are no existing videos to prove it! Regarding identification, unfortunately, insects are not my strong point. What I can tell you is that since it's a predacious diving beetle, it's most likely in the family Dytiscidae. This family, though, has many, many genera and species in it. The good news is that I found the following link that supplies a list, for Alaska, that narrows it down considerably: http://www.uaf.edu/museum/ento/Insect_Omnibus/Dytiscidae/ The next, tedious, step would be to go through that list and look up each specie on the internet. If you do a search based on images, it goes a lot quicker! I looked through about a third of those listed, and saw one that appeared similar - Dytiscus circumcinctus. Here's the link that shows this specie: http://www.hlasek.com/dytiscus_circumcinctus_ac7200.html Problem is, while it looks like yours does have something of a light border around the anterior edges, it doesn't look like it extends all the way around as is shown at the link. If this is indeed the case, then it's back to old drawing board - or in this case: the search engine!> Thanks for any help that you can provide. <You're very welcome, I just wish I could have given you a definitive answer!> Jack Adams White Mountain High School We are located on the Seward Peninsula in Northwestern Alaska. <Indeed a beautiful area, that's a fact! Take care --Lynn>

Tiny white bugs/crustaceans, FW... 8/29/07 Hi. Hope you can help me with this one! <Will try.> I have a 5 gallon freshwater aquarium with a betta fish in it. A few months ago I noticed a few things: 1) tiny white bugs, barely visible to the naked eye, that swim/jump through the water and sometimes scoot along the surface of the glass <Those are very small insects or insect-like animals. Thrips, collembolans, mites, and so on. Harmless.> 2) tiny things that stick to the glass and plants. They remind me of barnacles more than anything else. They are scale-like, flat, transparent beige in color, and have a small red-orange colored center. They start out as specks on the glass and progressively grow bigger, to about the size of a pin-head. They have a hard outer "shell"....I know because I've been killing them off as best I can ("crunch"), but they continue to multiply. <Sounds like snails of some sort. Basically harmless.> 3) tiny red-orange bugs that jump/scoot on the surface of the water, which remind me of mites or water spiders or chiggers. <Again, some sort of harmless arthropod. Quite possible red mites.> I have no idea what any of these are, and my internet research thus far has not helped. I'm wondering it is it possibly a single organism that I am witnessing at different points in it's life growth cycle?? <No, not really. Aquaria become ecosystems of a sort, and animals in house attracted to warm, damp places congregate on them. Hence you find the same sorts of things on the aquarium as you'll find in the bathroom.> A few weeks ago I did a major overhaul of my tank. I boiled the gravel, driftwood, and filtration components. I threw away all the plants. I replaced all but about 10% of the water. Two weeks later, there are tons more of the white bugs, and I'm seeing more and more of the "scale" looking things on the glass everyday. <You can't get rid of them. Remove them, and more will move in from your house. I'm guessing your tank doesn't have a proper filter; these little arthropods don't tend to be such a pest where the surface of the water is agitated by a filter. In "bowl" type situations, the still water surface is a perfect habitat for them. Furthermore, in betta bowls the water tends to have lots of nitrate and organic material in it because the volume is so small, and this encourages the growth of algae and molds. It is these that the little arthropods are feeding on. In bigger tanks with proper filtration, there's less of this stuff, and so the arthropods are less of a big deal.> These critters are such an EYE-SORE and NUISANCE in my Betta's home. Can you please help me diagnose this infestation and how I can get rid of them? <You can't. Learn to love them.> With gratitude, Shawna B. <Hope this helps, Neale>

Very Tiny Bugs on Water Surface 2/13/07 Hello, <Danielle> I have a 120G Amazonian community tank. It has been set up for about a year now and is doing well. I have noticed something curious when I do a water change: there are quite a few (30-50) tiny bugs that hop around on the surface of the water. <Neat> These bugs are very, very, very small (less than half a millimeter, I would guess), so small that I can barely see them and too small to photograph for you (I tried!) - and much too small for even my smallest fish to notice. I have attempted to catch one and look at it under my microscope, but have been unsuccessful. <Ahh, at least a "B" for trying> I only notice them during a water change when the surface is more than 2" below its full level, the water is still, and my four 65W compact fluorescents are on - I would not be able to see them otherwise. The bugs do not seem to be swimming or in the water column. They do not walk on the surface; they just hop (and hop quite high). <Some lessons in water tension now!> Their shape is that of a new-model VW Bug, flat on the bottom and a slightly slanted semi-circle on top. They have a distinct pair of antennae set at about 70 degrees from their body; one antenna is set at about 90 degrees to the other. At first I thought they might be dust mites, but dust mites do not have antennae. <Correct> They are much smaller than fleas (which do not have distinct antennae either). Have you noticed these in your tank(s)? What are they? Thank you, Danielle <There are a few groups of "water riding" insects other than the well-known striders (Hemiptera, Gerridae)... however... what you have here is likely juveniles of this family... do take a look-see re... These very likely "came in" with some of your plants... and will cause no harm. Bob Fenner> Sorry - in the third-to-last sentence, I meant "They are much smaller than fleas..", not "much bigger". Thank you! I greatly appreciate your efforts! Danielle <Ahh, will amend. Thank you, BobF>

Insect ID Hello, we don't know the name (scientific or common) of this insect and would like to do some research into exactly what it is. Do any of you WWM Crew know what the scientific or common name of this is so we can study up on it? We have never seen anything like it until we found this where we work. The head and front legs are bright yellow and the rest of it is dark purple. The tail is at least 4-5" long. I am sending a picture. Thanks for any help, Jeff <Nice pic. Does appear to be a species of Mud Dauber Wasp (Hymenoptera: Sphecidae). You can "look up" much info., other pix with these names on the Net. Bob Fenner>
Re: Insect ID Hello again, it is a wasp then with stinger as well? <Not necessarily> I assume the extremely long tail thing is not the stinger but is in the rear of the insect? <Yes> I entered the name you sent in your e-mail in ask Jeeves but am only coming up with pics of the common mud dauber that you mention and that I am familiar with. Any more clues that would point me to better pics with description on the web? Thanks ever so much again, Jeff <Do try Google... and words like "flying insect/s" and your State, general geographical area. Bob Fenner>

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