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FAQs on Aquatic Insects and Freshwater Aquariums 3

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!

Freshwater Bugs Identification and course of action needed    7/26/19
Good Afternoon. I have a 100 gal freshwater tank with male peacocks, giant danios, and Synodontis petricola. Tank is established with canister and sponge filtration, lightly planted, and no new fish have been added to the tank recently. Parameters are good, a little high on nitrates but adding extra water changes. I found a number of extremely small critters just above the water line that appear to be feeding on a flake of food that stuck to the side of the glass. They move around a good bit, appear to fight with each other, but I just would like to know what they are and make sure they are no threat to my tank. The photo enclosed is very magnified.
Thanks, Cindy.
<Hello Cindy. These are probably members of the Collembola, colloquially known as Springtails. They're completely harmless, and as you observe, feed on organic detritus in damp areas. Most aquaria have them, but sometimes they do 'bloom' if there's a lot of food for them. If you regularly wipe down the glass above the waterline, and avoid overfeeding, you can control their numbers, But in all honesty, I'd ignore them! Cheers, Neale.>

Worms     1/20/18
Hello my name is Mehrr, and I've found these work like creatures in my fresh water tank. Could you please tell me what they are?
<Are these in your aquarium? Seems odd. These are maggots of some sort -- larvae of flies (i.e., Diptera) -- perhaps houseflies or blowflies.
Harmless, and most big fish will eat them very readily. They do not live underwater though, so more likely have fallen into the aquarium from above.
Cheers, Neale.>

Re: Worms
No, they were in my fresh water tank.
<Oh, I'm sorry, I'll issue a refund at once!>
It's a giant covered, concrete cylindrical structure used to store fresh water for domestic purposes.
<Not really what the volunteers here are expert in.>
Are they commonly found in such an environment?
<Maggots are terrestrial and must breathe air, but do prefer dark, damp environments with plenty of decaying organic material. Trash cans, compost heaps, rotting food are the sorts of environments they favour. Examine
where this tank is located and act accordingly. There are aquatic maggot-like animals of course, such as Rat-tailed maggots, that do live in swampy, polluted ponds and ditches, but they are very different in appearance to traditional Blow fly, House fly, and similar maggots. Cheers, Neale.>

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>

What is this?       5/30/15
I have put an avocado pit in water and after a few weeks, I found these worms in the water. The most pointy side are mostly at the top of the water, as if for breath!
<Can't really tell from your photo but description matches "rat-tailed maggots" which are the larval form of specific types of fly and very interesting beasts! Not many people get to see them, so well done! Probably better outdoors in some swampy bit of pond though. Cheers, Neale.>

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.

Re: Strange worms in tubes and algae       3/14/15
Thank you so much!
<Glad to help. 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>

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 ha-ha). 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!

little worm 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.>

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>

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