Killing Damselfly Larvae

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Jellibeen

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I have damselfly larvae in my shrimp tank. I have removed a few, but my shrimp numbers still seem to be dropping. My plan right now is to move my shrimp into the other 10 gallon (is already set up and has the same type of shrimp in it), and add something to the tank to kill the nymphs.

Does anyone know what i can use? I think medications that are not invertebrate safe would kill them. They are invertebrates, after all. I have read that chitin inhibitors would also work, but i am not sure where to buy that. I know i could get some invertebrate unsafe meds from the fish store. I don't know which medications would work, though, as i avoid anything like that since i keep invertebrates.

I don't think a snail killing product would work because they have exoskeletons. Anything copper based should work, right?
 

Donovan Jones

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Puffer maybe, or even a cichlid or gourami. Never tested it but I'd imagine that'd help.
 
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Jellibeen

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That wouldn't work. It's a 10 gallon shrimp tank. I don't want to add any new inhabitants, especially ones that will kill my shrimp once i return the shrimp to the tank.

Edit for clarification: The plan is to return the shrimp to the tank once i have killed the nymphs.
 

Donovan Jones

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If you have tons of plants the meds are your best bet but I would do at least 10 95 percent water changes after it sets for a week or two just to be extee safe for when you add the shrimp
 
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Jellibeen

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I would also get a copper absorbing filtration media.
 

Donovan Jones

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An alternative would be to bleach dip plants, plenty of vids out there on it, and then siphoning the gravel or sand to remove any hiding in there. It'll be a bare atnk so you'll see them. I'm gonna assume u use a sponge filter. I'd bleach dip the plastic then inspect the sponge pieces for the lil buggers
 
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Jellibeen

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I don't use a sponge filter.

It probably is a better idea to remove all the shrimp, then do a thorough cleaning. I don't think i want to do bleach dips on the plants unless i have to.
 

Donovan Jones

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What kind of plants do u have? I've had some come in on plants that seemed fine, but they hide exceptionally well. If u have any moss, odds are they're in there
 
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Jellibeen

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Java fern, hygrophilia, some vals, anubias. I've caught two so far and found a damselfly outside the tank.
 

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At risk of sounding like the died-in-the-wool old codger I am...I simply cannot imagine dosing a tank that small with medication or pesticides to handle damselfly nymphs. They are not that small, and there cannot be that many of them. If you find a chemical agent that will kill these arthropods, and then do something to remove that agent before you return the rightful arthropods (the shrimp) to the tank, well...great, maybe...but...

If you have another home for your shrimp, maybe capture as many as is practical and move them. The damselflies can by caught individually and removed/killed. They cannot reproduce in your tank, the number that is in there is finite and probably pretty small, so why not just pick them out over the next few days or weeks and get rid of them that way? Raising the water temperature to around 80degrees should make them more active and easier to spot, without harming the plants long term.

If poison must be used, then of course carry on. I just wanted to put an alternative idea out there. Good luck!
 

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Simply shaking the plants should get most off then. Be sure to check where all the vaplisneria leaves meet really well
 
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jjohnwm said:
At risk of sounding like the died-in-the-wool old codger I am...I simply cannot imagine dosing a tank that small with medication or pesticides to handle damselfly nymphs. They are not that small, and there cannot be that many of them. If you find a chemical agent that will kill these arthropods, and then do something to remove that agent before you return the rightful arthropods (the shrimp) to the tank, well...great, maybe...but...

If you have another home for your shrimp, maybe capture as many as is practical and move them. The damselflies can by caught individually and removed/killed. They cannot reproduce in your tank, the number that is in there is finite and probably pretty small, so why not just pick them out over the next few days or weeks and get rid of them that way? Raising the water temperature to around 80degrees should make them more active and easier to spot, without harming the plants long term.

If poison must be used, then of course carry on. I just wanted to put an alternative idea out there. Good luck!
No, i understand that. Definitely does not make you sound like an old codger! That's what i have been doing. It's already been a few weeks and i keep finding more. I'm worried because more keep popping up, and i don't know how many more are in there. Maybe there were only three and i've gotten them all. I've been on the fence about undertaking more drastic measures. I'm not sure what the best course of action is, and i worry about my shrimp.
 

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The odds are they came in as eggs on plants. The fact that you found an adult would imply that they have lived out their underwater development and are starting to metamorphose into adults. If that's the case, your problem might already be gone.

Take heart, it's not like Ich where the tank contains thousands of individual parasitic organisms. These little predators are there in finite numbers, and even if you don't catch any more they will eventually transform and disappear. They are likely all at roughly the same stage of their development; if one has transformed they are probably all ready to do so.
 
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Thank you for your reassurance! I go back and forth between thinking it's fine, and total panic that all my shrimp are going to die. I'm also concerned because i haven't seen many shrimplets lately.

Another issue: research tells me that they lay their eggs inside of plants. How can i keep new plants safe? I really don't want to quarantine new plants. Would a bleach or copper dip do the trick?
 

Donovan Jones

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Quarantine the plants for however long it takes to hatch eggs and look to see if any show up. I'd use a bare bottom so you can see them easier
 

jjohnwm

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That sounds like the easiest plan. Again, warmer water will speed up the hatching process. This isn't a common problem (certainly not in my region!); maybe check with locals if it is seen often in your area. I doubt that it is.

I think the lack of tiny shrimp is related to the fact that when the nymphs hatched, they were very small and were predating on the hatchling shrimp. As the nymphs increased in size, so too did the size of the shrimp they killed.

Edited to add: I doubt that anything will kill the eggs before they hatch. After hatching? No idea...as I said, it's not something that we Canuckistanis run into very often.
 

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My browser is lagging. My response posted twice.
 

FreshwaterPhotog

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jjohnwm said:
At risk of sounding like the died-in-the-wool old codger I am...I simply cannot imagine dosing a tank that small with medication or pesticides to handle damselfly nymphs. They are not that small, and there cannot be that many of them. If you find a chemical agent that will kill these arthropods, and then do something to remove that agent before you return the rightful arthropods (the shrimp) to the tank, well...great, maybe...but...

If you have another home for your shrimp, maybe capture as many as is practical and move them. The damselflies can by caught individually and removed/killed. They cannot reproduce in your tank, the number that is in there is finite and probably pretty small, so why not just pick them out over the next few days or weeks and get rid of them that way? Raising the water temperature to around 80degrees should make them more active and easier to spot, without harming the plants long term.

If poison must be used, then of course carry on. I just wanted to put an alternative idea out there. Good luck!
I too am in favor of not putting anything dangerous in the tank if I don't have to. In the past, I thought it was a great idea to get mosquito larvae out of my birdbath (I was gone over the weekend in Arizona and found them when I returned). Normally I would change the birdbath daily. I thought of mosquito larvae as a bonus, a treat for my fish! I used a syringe and fed them to my fish.

About 2 weeks later, I spotted my first damselfly larvae. They look so big and scary in your tank! I'm sure my fish and shrimp thought so too! Once I knew they were there, I used my small net to catch and kill them. I kept an eye out. I ended up with 3 in my 55-gallon fully-planted tank. I felt just terrible that I had let loose some serial killers into my show tank.

It shouldn't be that difficult to be diligent in a 10 gallon and manually remove them. Just my experience. I believe manually removing the nymphs verses dumping in chemicals is the lesser of the two evils. If they came in on plant purchases, do a plant dip prior to installing the new plants into your shrimp tank. I believe prevention is definitely better than having to treat the tank with anything.
 
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I’ve seen them in the plant tanks at my LFS. They have beautiful plants, but hitchhikers are a problem. Many people grow plants outside in the summer. It’s cheaper. Plenty of light and warmth. Then the plants get put in aquariums, eggs hatch, and eat my precious shrimp.

It takes a few weeks for the eggs to hatch. The nymphs can live for years, which is another area of huge concern for me.
 
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Prevention is better, but they are already in there. What would you recommend using as a plant dip to kill eggs? They’re also inside the plants, so i’m worried a quick dip wouldn’t be enough.
 
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