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post-2809-0-50126200-1443599955_thumb.jpBoy when it rains it pours!


So last night I'm taking a few precious moments to watch my big tank.  


This is a 75 gallon, heavily planted with lots of structure.  I built it specifically for my caridina shrimp.  I wanted to throw a whole bunch of different ones in there and just watch the beauty that they are... and hey.. who doesn't want to have pinto shrimp?


So in this tank we have SSS red and black crystals, Orange Eye Blue Tigers, Tangerine Tigers, Black Tigers, Red Tigers, Red and Black Tibees, Blue bolts (some really fantastic colored ones too!) Red Wine Taiwan Bee, Black King Kong, Yellow King Kong (with lots of babies!), Black Panda, Shadow Panda, Red Panda, and lots of babies all over the place.  It is a tank I really love, and tomrrow I'm schedule to get 75 more shrimp to put in - more pandas, red bolts, more blue bolts, more red wines...


Watching this tank is really something I adore doing.  It has a prominant place in my living room.  I have three shrimp rooms now where I don't really get to watch my shrimp, but this tank is kind of my pride and joy as far as the shrimp.  Of course it has its obligatory share of pond snails.  I'm sure those little suckers can slide across my flooring to plant themselves in tanks they aren't supposed to be in. There's a few ramshorn snails..


Then tonight, I see something that freaks me out a bit.  There's a bug in my tank!  Its not a worm.. its an actual swimming bug.  For a moment I think a spider got in the tank.. but this has 6 legs.. ok .. officially icked out here.  I go to catch it and then do some research..


Apparently this is a dragonfly nymph... uh oh.. they eat shrimp?  Good thing I caught it..


And then I see another

and another... god they are everywhere!


I end up stripping this tank down to the substrate.  I have no idea how many baby shrimp I may have killed when I pulled all the wood and stone and plants out.  I was as careful as I could but... 

I also pulled out more than 100 of these dragon fly nymphs!!!!!!!  How could I not see these disgusting predator bugs before .. and how in THE hell did they get in my tank? 


Now my beautiful tank is just substrate.  My shrimp have been completely stressed out.  And I've caught all these bugs.  I have all these berried shrimp in there.  Who knows how many are going to kick away eggs as a result of this.  Who knows what was pulled up with the plant roots...


I'm beside myself.  I literally have thousands invested with this one tank.. and ..bugs?  I can't even begin to imagine how bugs got in there. Some were tiny and some were larger than my shrimp.  Where did they come from? .. I haven't put anything new in the tank since it was set up and that was more than 3 months ago. .. have these things been in there the whole time, hiding out of sight?  I can't say.  What I can say is I've destroyed my beautiful tank.  I'm afraid to put anything back into it and afraid to buy anything new for it.  Apparently dragonflies lay eggs inside plant leaves.  


At this point I am thinking I'll get plastic plants!


What a nightmare!!



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This was the tank back in mid august when it was still fairly newly set up.post-2809-0-17754100-1443600425_thumb.jp

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so sorry to hear about this.


now I could be wrong about this, but I don't think the nymphs can lay eggs until they develop into the adults, so once you've killed/caught all the nymphs you may be OK.   I got 2 in my Sulawesi tank once, had to fish them out too, but after I got them I didn't find any more and my shrimps were fine, babies included.


Hopefully you've got them all.  Is your tank completely covered on the top?   If there's a gap anywhere I think I would maybe put some additional covering so this doesn't happen again. 

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It sounds like you have dragonflies that are laying eggs throughout these three months. This will be your main problem. The nymphs (if any remains in the tank) will feed on a few more shrimps and turn into dragonflies. As strange as this sounds, but is there any chance dragonflies are laying eggs in your tank? They lay from the water surface. You also mentioned that the last time you added anything to the tank was when it was set up. Did you add all your shrimps at once too? Is it possibly that the eggs are making their way into your tank when you're transferring shrimps to your tank? I hope these might help.

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Hi Cheryl,

While I usually just ask questions or offer opinions, this is an area in which I do have some helpful experience having worked with aquatic entomology in the past. Monty is exactly correct in that the nymphs cannot reproduce. Both dragonfly (wings flat) and darning needle (wings upright) nymphs look somewhat similar and both are great predators. They have a life cycle that can last up to 2 years in the water and an adult may have gotten in and laid eggs from the top. Whlie I wouldn't want them in my shrimp tank, they are fascinating in their own right as well as being beautiful and fantastic predators to mosquitoes and such as both larvae and adults.

I'm sorry you had them in your tanks, but like Monty said, and it bears repeating, they can't reproduce in that state. Also, like so many other aquatic critters, they can grow at different rates so different sizes doesn't necessarily mean different batches of eggs.

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Good morning everyone,


Thanks for all the helpful replies.  After laying awake most of the night thinking about this, I believe I've come up with an answer. I bought some plants for the tank back when I was setting it up, and the seller mentioned keeping them outdoors in ponds.. growing them emerged, and that they may lose leaves when they were submerged.  Some dragonflies lay their eggs inside plant leaves that are above the water, and the eggs hatch when the plants are submerged.  So.. there you have it.  These things have likely been there the whole time and just out of eyesight.


I do have the tank completely covered. .. they all are.  I have cats, and one that isn't too bright and has ..taken a bath a few times when I'm doing maintenance.. funniest thing ever, but she doesn't think so.


I've only caught one of the evil buggers this morning, but I'm holding off putting any structure or plants back in until I am reasonably sure no others are in the tank.  I plan on washing everything copiously before putting it back in the tank.  Real shame too, because I was just getting some of the moss to adhere to the rock... it was really starting to look nice.


It looks like i've lost several shrimp from last night's debacle, and wouldn't you know it? .. one of the bags of my new shrimp somehow split in the box, killing all the lovely blue bolts inside... poor things.

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Very sorry to hear Cheryl. I would of loved to of seen more of the shrimp tank. Hopefully you can rid the tank of the nymphs and start fresh.


Thank you for sharing!

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What a beautiful tank.   What a pain in the A**.   I have nothing to offer but sympathy since I know nothing about these bugs  but wanted to throw my support in with everyone elses

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Hi guys,


Just to be clear.. my tank is covered.. they all are. cats and such.


I did not do a plant dip... I have read about it .. dipping them in bleach for a couple seconds, but I have never done it.  The interesting thing to note about these bugs is that they are tough!  I played Mengele with these guys last night.  Put peroxide on them... they shrugged it off.  I salted them in the peroxide.. nothing... went for the rubbing alcohol... nothing.. they just ignored it.  I finally flushed the mass of them.   I wonder if a bleach dip would have worked.


I thought I had them all.  But when i started really looking again, and started paying attention to the large sponge that covers my filter intake.. shesh, they were everywhere.  I bet I have pulled another 50 of them out of the tank!


No wonder I was missing shrimp and never found bodies.  I always though if one died it went into the structure where I couldn't find it ... but I never found any dead ones when I pulled everything from the tank either.  I bet these guys were having themselves a feast on my shrimp!  Disgusting little things. .. they give me the creeps... like a cross between a tick and a spider.


So I have a few questions for all of you...


1. I am assuming, but figure I should get other opinions - should i throw away all my plants?

2. Is it safe to use the wood if I wash and scrub it well or is that a goner too?

3. The stone should be ok, yes? .. Obviously its going to get a good rinse and scrub with a brush as well..

4. Lastly, can these things exist in the substrate as eggs for any length of time?  IE - do i have to throw away the substrate as well and start all over?


Thanks everyone.. your input is greatly appreciated!




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Sorry to hear of the battles here - not fun at all.  I had a nymph problem as well, but turned out to only be one, so I was extremely lucky.


If I were in your position, this is what I would do - this is just me, not saying this is the right way by any means, but what I would do to sleep at night.


Note: Infected here just means the tank that has the nasty critters in it.  This would not work with a water based infection, etc.  I just use infected to keep the tanks differentiated.


1. Go out to Petco and get a new 20L tank (I have heard they are on the $1 a gallon sale)

2. Bring the new tank home, leave it bare bottom

3. Move a bunch of the water from the infected tank over to the new tank

4. Hook your filter up to the new tank

5. Move the shrimp - all that you can catch and have the patience to catch over to the new tank

6. Add some java moss (new, outside of your house) if you can find some to the new tank - just to give them some cover and something to graze on.  You don't need a ton of it.

7. Take the old tank out to a backyard/garden space, somewhere, and flush it completely out with a hose.  Use a spray nozzle if you want, just wipe it completely out.

8. Make a mild bleach solution and scrub out the tank - use a bit of elbow grease - you don't have to go crazy, just thorough.

9. Rinse the tank really well again

10. Pick up a buffering substrate of your choice.  Maybe ControSoil or Fluval if possible.

11. Fill it up with fresh water (remineralized if you do that, etc)

12. Let the new tank sit overnight.

13. Early the next day, move the filter over to your "old" tank that has now been refreshed

14. Run the filter on your refreshed tank for 24-48 hours.  Test params to make sure you don't have bad params (ammonia, nitrate, etc)

15. Move the shrimp back to your refreshed tank

16. Populate your refreshed tank with new plants/moss.


Again, this is just how I would handle it if it were me.  I have been burned too many times by trying to "save" stuff from a tank that went bad.  I almost always ended up regretting it.  I have been much further ahead to start with clean, new plants, etc.  Maybe this is overkill, but plants for the most part are cheap.


Hope this gives you some ideas, definitely modify as you see fit.  The shrimp in the 20L tank would be fine for a few days without the filter in a bare bottom tank. You could even run an airstone if you were really worried, but should be OK.

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If I get a chance I'll look into their lifecycle. I think the plants and substrate are the biggest issues. Plants should be OK with a permanganate dip. Not sure if nymphs would be affected, but it is the strongest& safest dip, afaik. Works for stones and wood, as well. Not sure what is best to do for the substrate, I should think you could scoop it out and soak it in permanganate, as well.

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Yep those are dragonfly larvae. They are predators as you found out but they will not lay eggs nor breed, not until they morph into adults dragonfly (the big flying guys). 


Keep in mind that some of those larvae will bury themselves and wait for the prey to pass by and then launch their 'mask' and catch them. 


I would boil anything i could to make sure that anything newborn larvae will die (they are good at griping themselves to rocks and become quite hard to see), I would pick up the plants and put them emerged in a container for a couple of weeks just keeping them moist enough to survive but anything else would end up falling into the container and dying. 


For the substrate if you can buy another go for it and dry this one out for some month's.


Keep in mind that some species of dragonfly larvae will stay in that form for up to 3 years before becoming adults.

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Great advice.. and thank you guys so much.


So I am fairly certain I got them all.  I spent several hours staring, searching, hunting the little bugs and nothing.  So, I boiled my stones and wood.. and placed them back in the tank.  I'm figuring the plants are goners . .. I had some really delicate ones and I don't think they would survive a bleach dip (would love to know what a  permanganate dip is!) .. I have them in an empty 10 gallon.  This is my hail mary.  Otherwise, I have 10 bags of ADA soil actually on the way to me, and empty tanks for it, so I can rebuild the tank if I have to....

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Ah that was one thing... I was wondering if they would bury themselves in the substrate.


That would certainly change things.. ah I was hoping for a different outcome.


Guess its back to the ole drawing board with this tank.. I'm so very sad.

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Don't desperate as long as you can keep your remaining shrimp safe until your new substrate arrives everything will be fine! Then just remove everything from the tank, clean it and rebuild. Keep in mind that your substrate wont be lost just need to dry it out for some time and your more resistant plants will probably survive too.


Keep the plants more delicate on another tank for some time, if there are still some larvae/eggs on them they will eventually grow bigger and easy to see and catch since they can't breed its just a matter of time. 

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So sorry to hear, I know how it is having to redo tanks and stuff, not fun! Looks like everyone else gave good advice.

I use alum (you can buy it in the baking section) to dip your plants, it works even with sensitive plants. I've soaked plants for two days before without harming the plants.

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Potassium Pomergranite   However its spelled.    Go to Walmart and there is a product there by Jungle called Clear water in the fish section.   (or get it on amazon)   That is Potassium Pomerwhatever. 

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I just did a quick search but could not really find a good reference as to what exactly PP (pomegranite, lol. Potassium Permanganate) will treat, and it can damage some plants.

I found one post by a person saying a dip in salty water (concentration unspecified) took care of nymphs and leeches.

If the nymphs are large enough, hopefully you can just hand pick them, but I don't know how large the eggs are, that might not have hatched yet.

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Permanganate can also stain skin and discolor stainless steel, so have a care. However, it is a nice disinfectant to have as it is easily countered with peroxide in case of an overdose. The same can also be said of bleach, of course.

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Hi everyone,


Well .. here's an update:


I mentioned I put my rocks and wood back into the tank. 


Total I think I got almost 200 of the evil buggers out of my tank.  I haven't seen any since yesterday afternoon.  I have all the plants in a ten gallon I had just started.. so ..we'll see what happens there. I'm pretty much writing them off.  


I only lost a couple of shrimp due to the chaos.. one for certain.


Everyone is doing fine today, and though there are no plants, I do have a metric ton of moss I can pilfer from a bunch of tanks that I can throw in there.  I'm just making sure I don't see any bugs for quite some time.


I'm going to be separating out everyone into smaller tanks, and leaving only one or two strains in the large tank so I have pure colonies .. I have smaller tanks that are free where I can play mad scientist and try for interesting shrimp (read pintos here) ..


Thank you so much for all the advise.  I can't tell you how much it is appreciated.



Minnesota Aquatics

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