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FAQs on Aquatic Insects and Freshwater Aquariums: Dragonflies, the Odonata

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, Flies in General (Caddis, Gnats, Midges...), Freshwater Mites, Mosquitos/Mozzies and much more!


Dragonfly/Damselfly issue 1/19/12
Hi there!
Ok, so the other evening I found what was either a dragonfly or damselfly (can't remember what the wings looked like)
<Mmm; easy to tell apart, the latter can fold their wings over the axis of their bodies. Odonatans, no:
http://bcadventure.com/adventure/angling/bugs/damselfly/damselfly.phtml >
on the edge of my aquarium light! Don't ask me how it got into the house, it just did. So I'm thinking, 'Great (a sarcastic 'great')! Its laid eggs and I'm going to see nymphs in my tank!'
<I hope not Odonatan!>
I got a bit annoyed and blew at the poor creature to force it to land in the water, forgetting that they can probably repel the water tension as was the case here. It flew up to the glass brace bar of the aquarium and I felt bad and took pity on the thing.
I got my net and rather easily caught it and took it outside and released it. It was a very beautiful deep crystal blue.
24 hours later,
I spot what I at first thought was a dead cherry shrimp laying at the bottom and foreground of the tank. Upon closer visual inspection I realise that I'm looking at a dead nymph (I guess one of my dwarf gourami used it for sport after realising it was a bit big to fit in the mouth comfortably) as I had earlier feared. The problem is, it was only 24 hours later and this thing was already approximately 10mm in length. Could it have hatched and grown this large so fast?
<Don't think so; no. Perhaps a previous visitor...>
Were they both possibly from a same batch that hitched a ride in my blackworm feeder water and one just happened to develop and moult faster than the other (latter seems unlikely since I've read that nymphs will spend up to 3 years in its larval form where there is a plentiful water supply and food source)?
<Mmm, maybe>
The problem I am facing is that I have lost A LOT of red cherry shrimp which I put down to our summer weather, but now I'm starting to think that nymphs may have been behind these mysterious disappearances, especially if one developed to the point that it was large enough to moult and escaped my attention till it emerged. I still have a couple of female cherry shrimp carrying eggs and I'm concerned that there may be more nymphs hiding in the aquarium.
<I'd dismantle... take a look... you should be able to see if there>
I have nothing against dragon/damselflies at all, in fact I find them very beautiful and extremely beneficial
insects at pest control, but they have no place in my tank if it means that I lose most if not all of
my cherry shrimp.
<I suspect something else is going on w/ your shrimp mortality. Please peruse this file:
In particular, are you feeding enough, is there sufficient room? Do you dose Iodide/ate? What re biomineral and alkalinity here?>
I also found a dead adult male cardinal tetra the morning before I saw the dragon/damselfly. Are they tough enough to kill a cardinal tetra or would this have more to do with water conditions or aggression from a spawning male dwarf gourami?
<Dragonflies can catch, kill quite large fishes. Yes>
What would you recommend I do?
<Reading the citation, answering the questions, dismantling and looking...>
I don't have a second tank to transfer the fish and shrimp and I don't really want to tear the tank up looking for nymphs anyway. Any other solution besides just keeping an eye out?
Thanks heaps,
<Cheers, Bob Fenner>
Re: Dragonfly/Damselfly issue 1/20/12

Hi again,
My aquarium critters may have to take their chances for now since I have no way of housing them
while I tear their home apart.
<Mmm, can be just placed in a chemically inert container for the less-than an hour time this should take>
My apartment is tiny and I can't afford a second, smaller aquarium right now.
<Don't need>
My water is pretty hard, although I don't think it has any concentration of copper
<Mmm, no. Your shrimp would be dead>
(I don't have any test kits besides a liquid ph kit which is basically useless since adjusting the ph in hard water creates an unstable environment) and I've been careful to avoid any products containing copper. I have laterite in the substrate, but apart from this I don't use any supplements, bio or chemical in the water (except of course dechlorinator, but not really a supplement... more a conditioner).
The tank is 36" long by 14" high and 12" deep and medium to heavily planted. Besides the cherry shrimp it houses 1 male gourami, 2 female gourami, (now) 5 cardinal tetras, 2 false julli eye Corys and an albino Bristlenose so there should be ample room for the shrimp and a forest of hiding places with plenty of open swimming space near the top for the fish.
I feed the catfish about 3 sinking wafers a week in addition to a reasonable amount of leftover food plus a large amount of java moss too. The fish are fed frozen brine shrimp, fish flakes, frozen bloodworm
<See WWM re these sewer fly larvae... I'd cut out>
and live blackworms alternately so they lack nothing for variety.
I also do weekly 25% water changes.
My other suspicion that I have yet to prove is that a lot of the baby CS were sucked into the filter inlet, but this doesn't account for the many missing adult CS that are too big to be sucked up. I occasionally still see a few baby CS crawling around in the java moss and in the forest of chain dwarf Amazon swords I'm training to cover the foreground.
So if you don't think its the nymphs causing the havoc, I may need to take a sample of my water to the LFS to test for ammonia, nitrite etc,
<Better by far to have/use your own kits then and there... samples change w/ time, moving>
but I did believe that the lack of animals, the size of the aquarium and the density of plant life in the tank would take care of this for the most part.
Although I don't use an air pump, I always raise the canister filter outlet above the water level at night to achieve adequate aeration for both plants and fish. Most of the plants pearl nicely during the day so I'm guessing there should be plenty of air in the water during the day. I also use DIY Co2 injection.
<This too could be problematical...>
Anyways, I hope this answers most of your questions about the condition of my aquarium. If you don't have anything else you could advise I guess I'll just have to play the 'wait-and-see' game.
<A good plan>
Thanks again.
<And you, BobF>

... English? Shrimp... Odonatans... 1/11/11
okay in my shrimp tank I have some kind of dragonfly naiad(I think that's whats its called) It has six legs black in color( i seen a pic on one web site but it didn't have a name they just called it a dragonfly naiad-- and you have to have permission to use the pic.)
I need to know if they would eat my shrimp.(Ghost & Cherry)
altho I have lost about 14 (combined) of them. I wrote before about some kind of worm/snail that Ive been taking out when i see one, and they will not live out of the water. usually about 30 sec or so they dry up. they are very soft body, slimy feel, black in color (Looks white inside on glass) long bodied but can move like a snail but it only attaches with the head on the glass. head is traingle when streched out. is this part of the dragon fly i found and could there be more since i found this big one in the tank.
unfornately the tank is filthy but cant clean it due to the thousands of (ihope )baby shrimp
need help with that also anyway anything on the creatures would be nice and if you want i could send actual samples of these creatures.
<Uh, no... see below... need to be removed likely>
Judy Potts
<Judy, please run your writing through a spelling and grammar check before sending. See Net re how to do this if unfamiliar.
And read here: the http://wetwebmedia.com/FWSubWebIndex/fwaqinsectfaqs.htm
Bob Fenner>
re: 1/11/11
Okay so sorry for the misspelling here. I went and saw what the creature was and a gentleman named Neale said it was a Odonata.(on the website)
Since that what it is,What do the larve look like?
<? Look up via your search engine/s... Dragonfly Nymphs...>
Is it best to take out the grown shrimp and just clean the tank?
<... read where you were referred. B>
What should I do? I also notice white creatures round body with two little white dots following the round body.(Magnafing glass helps) The others look like the baby shrimp I thought they were,but not growing at all. They have the long body and really look like shrimp. I apologize for not being more informal on the topic, but Neale has helped me so many times that I trust you with the info that is provided on your website. Again I hope I did a better spelling than before.LOL
Judy Potts

Strange critters in my tank(s), FW aquatic insects 2/1/08 After several days of scouring the web for answers, I'm still no closer to identifying this critter. So far I have found 3 - two very tiny, and one that's now about 3/4 inch long. When I saw them swimming I observed that they moved with a sort of eel-like motion, but they are definitely not worms (as I thought when I had only seen the tiny ones). These have 6 jointed legs (looking much like a spider's legs) at the "head" end, no legs on the bright green body (which looks to be segmented, but since it is so small it's hard to tell). It's about as thick as a pencil lead and at the other end is a sort of finned tail with 3 distinct "fins" which, unlike the body, are marked with dark bands. When resting right-side-up, this critter uses the two outer "fins" to hold up its tail end, and the middle "fin" stands straight up. When swimming the "fins" are folded and look like a darker extension of the body. When the critter (presumably) sleeps, the fins are also folded together and the 3 separate appendages can't be distinguished. I found the first of these when I was doing a water change in the large tank (200 liter) and the second and third while doing a water change in the fry tank. The first two were less than 1/4 inch long and the colors were not apparent at that stage. They just looked like short, very thin wiggly things with larger heads and I first assumed they were some type of worm. However, given the 6 legs and fin-like tail sections I realize they're totally un-wormlike. Not knowing what they were, I put the largest of the 3 in a small glass of water and he's been there now for a couple of weeks. In that time he hasn't gotten any bigger, and crumbs of fish food went untouched. A few days ago I put in some dried and fresh bits of various leaves to see if he would eat them. Until then he had stayed at the bottom of the glass, supporting himself on his legs and the two outer "fins" - but the first day he somehow noticed the floating vegetation (I say "somehow" because before then I had never seen him move from the bottom, do any exploring, etc.) and has now relocated himself to the underside of a floating bit of (dried) leaf, folded his "fins" and settled in at his new location. It's just not possible to get a good photo of him - though I did try - so that his head, legs and "fins" are visible. The fry tank sits on a low table beside a medium-sized potted Sheffler which from time to time gets infested with those tiny pesky gnat-things that crawl around on the surface of the potting medium. Not whiteflies, but I don't know what they're called. However, I've never seen the gnats look anything like this in any stage of their development, and there are no other plants/pests in the immediate vicinity of the tank. The little table is, however, next to the balcony door (which I tend to leave open when the weather is nice, though that doesn't happen often here) and on the balcony I have probably 60 or 70 plants of different types, none of which have had any pests aside from the occasional snail. I considered the possibility that my critters came in from the outside and from there to the fry tank, possibly transferred to the main tank on a communal net or something. But that's quite a bit of guesswork, and I'd like to know for sure what this is and what (if anything) I should do about it. My partner thinks they're mosquitoes. However, we have had sub-freezing and inhospitable weather this winter, and I can't imagine that mosquito larvae would be already hatching. It hasn't gone above 8 C. for at least two months. In addition, this mystery critter is already bigger than any mosquito I've ever seen - even in southern Louisiana. :P Does anyone have any ideas? Please? Hopefully, Erin <Erin, without a photo difficult to say, but if the thing has three filaments (actually gills) coming from the tail-end, then it's mostly like a damselfly larva (Order: Odonata; Suborder Zygoptera). Quite common in ponds, and they sometimes get into aquaria with live food or on plants. They are predatory, and eat things like smaller insects as well as fish fry. They won't (likely can't) eat dried food. Cheers, Neale.>

Water Bug? -- 10/18/07 I'm not sure what it is or how it got into my tank. Is it potentially dangerous to my fish? Could there be more? It's a little less than half an inch. My apologies for the bad picture. <It's almost certainly a dragonfly (order Odonata) larva of some type; and yes, they're predatory. Absolutely fascinating animals to keep in their own aquarium or bowl, but not safe with fishes. Easy to keep, and you can even hand-feed them bloodworms using forceps or similar. Take many months to mature in some cases. Impressive jaws, and if anything these insects are even more interesting than the fish we commonly keep. (Rather like mantis shrimps, which are *far* more interesting than the average coral, despite being viewed as pests!) Usually these things get into tanks with live food or aquarium plants. The parents lay the eggs directly in the water, and the aquatic larvae can't fly from one pond to another. So it got into your tank because you put it there, albeit unintentionally. Cheers, Neale.>

Re: Loach ID 7/26/07 Wow, thanks for such a quick response. You nailed it: Misgurnus anguillicaudatus, Dojo Loach/Weather Loach. About the nymph, a goldfish bowl is sufficient? And do I need real pondweed or would fake plants suffice? And I figure he'd eat just about any bug I throw in or do they have to be water bugs? I'm very excited about what you told me and not having to get rid of him. Should be very interesting! Thanks again -John <Hi John. Weather loach is a lovely fish. One of the nicest. Hardy, cute, fun to watch, hyperactive, and totally peaceful. Just for once, a "mystery fish" story has a happy ending. Anyway, yep, the nymph will be fine in a bowl. Change some of the water every couple of days just to keep things sweet. But damselfly nymphs especially live in still water and aren't fussy. (To tell the difference: damselfly larvae have three "feathers" at the tail end, used for breathing; dragonfly larvae are a little bigger and more robust, and they don't have those feathers.) Obviously a 5 gallon tank with a air-powered sponge filter would be even better. And yes, they eat pretty much anything. Soft prey are preferred (like midge larvae). The only thing that matters is there's something floating at the surface the larvae can crawl about on. They need to breathe air periodically. Good luck. Cheers, Neale.>
Re: Loach ID, now an Odonatan! 7/28/07
Hey Neale, thanks again. He's definitely a Dragonfly Nymph. Over an inch and he has 3 spikes on his end instead of feathers. I got him the biggest bowl I could find, 2 gallons and he's got some artificial plants to crawl on. Should I stick an airstone or sponge filter in there? I have both but they aren't in use. I threw a small feeder Guppy in there to see what happens, hopefully he can catch him. I just don't know where to find or what kind of food, live or prepared, to feed him. Any suggestions? I live in suburban Atlanta with a lot of woods but not many ponds or anything to speak of. Oh, and I noticed him sticking his tail out of the water just like you said, pretty cool. Thank you in advance. All the best, -John <Hi John. If you have a little sponge filter, then by all means add it to the tank. As you have learned, this nymphs breathe air, and this allows them to live in pretty swampy environments. But keeping the water clean will certainly help. In terms of food, they will eat very small fish. Potentially a guppy, though typically they feed on fry rather than adult fish. Otherwise, they will eat a variety of things. I've fed them using frozen bloodworms held in front of them with tweezers. If you have a garden or balcony, nothing beats setting up a "water feature" to grow your own live food. This is a good time of year to start one up, if you're so minded. Mine is a plastic tub that looks like a half barrel, and I stuck some sand and aquatic plants in there, plus the result of a few sweepings of the net in another pond. It now has daphnia, ostracods, freshwater amphipods, leeches, hydra, Tubifex worms, snails and all sorts of other small beasts. Many of these are useful and safe live foods for things like pufferfish and baby fish that are otherwise difficult to feed. Even if you don't have access to any real ponds, adding a couple bags of daphnia from the shops will get things started, and a lot of things, like insect larvae, will just arrive by themselves. I've even kept some tropical fish (peppered Corydoras) in there over summer, despite the lack of a filter. They not only did well, they bred as soon as I brought them indoors. So what I'm saying is that even if you don't have a pond, if you're finding keeping just the nymph fun, consider scaling things up to a "mini pond"! Cheers, Neale.>

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