# Shrimp attacking Planaria



## greenman857 (Feb 25, 2012)

Last night I witnessed a shrimp attacking a group of Planaria with no ill effects to the shrimp. I feel more confident now saying that Planaria probably never pose a threat to shrimp, but of course may compete for food.

I've been following threads with Planaria discussed.
http://www.plantedtank.net/forums/showthread.php?t=198521&highlight=planaria

I have a low tech nano tank with a diverse invertebrate population. Copepods, Malawa and Rilli Shrimp, Pond Snails and of course Planaria (Flatworms). 
http://www.plantedtank.net/forums/showthread.php?t=194049

I've always been concerned as to the Planaria's relationship with Shrimp.
I love the idea of a mix of organisms in a small ecosystem-like setting (and so am reluctant to treat). 

_I frequently see Planaria gliding on the glass. Last night I watched a group of Planaria writhing around, I'm not sure if they were mating or eating something but I'd vote for the former.Suddenly a shrimp descended on the mix and attacked the group, breaking everything up and eating something, and continuing to eat for sometime. Eventually the shrimp swam off. I saw a small flatworm glide off but the rest had either fallen to the bottom or been eaten (?). I watched the shrimp for a couple minutes and it seemed fine....  _

I only write this as an isolated observation and am not suggesting flatworms may not be a problem but just reporting what I saw.
One theory I have is that the shrimp are mostly out competing the flatworm for food, the shrimp are everywhere!


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## steven p (Jun 22, 2012)

Ive seen shrimp coexist with planaria at an LFS. I even kinda brought a few home with some suesswassertang... They didnt seem to even acknowledge each other...


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## GeToChKn (Apr 15, 2011)

Shrimp are detritivores, they don't attack alive things so I doubt it dove into a swarm of worms and attacked them.

Are you sure the worms are planaria? I've had many different kinds of worms that I thought were planaria, but turned out not to be. There is pictures and I believe even youtube videos people have posted of planaria attacking and killing shrimp. 

Maybe it is only one kind of planaria worm that we identify as the shrimp attacking kind, while the true meaning of planaria is the entire group of certain kinds of flatsworms, as some can live on land, in moist areas, dry areas, some are underwater, some are freshwater, some are saltwater, so perhaps us "shrimpers" use the term more specific for a certain kind common to freshwater tanks and being submerged that attack shrimp, but it does happen. 

You have many other worms or they just didn't get to attack the shrimp, but I still highly doubt the shrimp went after worms, they were alive.


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## wicca27 (May 3, 2009)

GeToChKn said:


> Shrimp are detritivores, they don't attack alive things so I doubt it dove into a swarm of worms and attacked them.


i beg to differ with this statement as i have had shrimp kill all of my limpets (yes i kinda liked the little things) and also would eat the baby rams horn snails. they dont bother the big ones but the new hatched and up to about pin head size i would find dozens and dozens of shells where the shrimp pick them and eat them. and its been known that they can attach each other and kill each other right after mating and ghost shrimp are bad about this. it was my oebt that would eat the snails and lipets though. heck ive had crs whipe out my assassin snails that i put in the tank to get rid of the rams horn over population.


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## mordalphus (Jun 23, 2010)

Your logic is flawed. Shrimp attacked planaria, therefore planaria do not attack shrimp?

There are several kinds of planarian, and although some MIGHT be harmless, there are definitely kinds that harm and kill shrimp. 

I have witnessed it with my eyes, so I know that it happens. My logic is: Planaria attacked shrimp, therefore planaria attack shrimp


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## dougolasjr (Mar 3, 2010)

I wouldn't trust planaria.


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## Betta Maniac (Dec 3, 2010)

GeToChKn said:


> Shrimp are detritivores, they don't attack alive things so I doubt it dove into a swarm of worms and attacked them.


My CBS catch and eat the live "blood worms" (I think they're really tubifex) that I feed to the betta in the tank. They even fight over them.


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## greenman857 (Feb 25, 2012)

I am sure the shrimp attacked the Planaria, I've researched them enough to recognize them. and I'm certainly not saying that Planaria won't attack shrimp but, I guess I felt I wanted to clarify that Planaria aren't voracious shrimp killers that have to be eliminated.
Possible thoughts
1) I have Malawa maybe they don't have the same sensitivity as the Neocards?
2) there is species differences in Planaria as to aggressiveness etc.

As for the picture, it doesn't quite make sense, how did so many Planaria get on the shrimp?, shrimp are so much faster, I'd like to see a higher resolution photo. Certainly anythings possible but I think that pic is a very rare unusual event...


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## NWA-Planted (Aug 27, 2011)

As i was reading this post i watched my shrimp fighting each other over food lol. I have even watched them Chase my pygmy Cory away

Sent from a dark corner in my happy place


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## ravensgate (May 24, 2012)

greenman857 said:


> As for the picture, it doesn't quite make sense, how did so many Planaria get on the shrimp?, shrimp are so much faster, I'd like to see a higher resolution photo. Certainly anythings possible but I think that pic is a very rare unusual event...


Go look at youtube. I know there are at least a couple of videos of planaria attacking and killing shrimp.


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## greenman857 (Feb 25, 2012)

Checked youtube, here's what I found
https://www.youtube.com/watch?v=WuHd_cP7FeY
Planaria attack kind of but shrimp swims away
https://www.youtube.com/watch?v=GTrDwebzaIM
Planaria attack but the shrimp looks dead...
https://www.youtube.com/watch?v=f8hZIJwPhUU
Described as attacking but looks like shrimp was dying?
https://www.youtube.com/watch?v=gqSqKyRQyhc
This seems pretty bad but I think shrimp is dead here too?
https://www.youtube.com/watch?v=oJqwOS_udNs
Shrimp and Planaria feeding together!

I did come across this though....
_This is from the paper I've 5 year ago. Planaria & hydra are the only 2 known pest that can kill shrimp. Planaria have this toxin which are use for self-defence against any moving object. It only work on close proximate. Didn't say anything about toxic being in the tank until it reach a deadly level for shrimp, I guess with being that small will take forever to get to that level thus any water change will dilute it.
It also stated that since shrimp are scavenger, the will eat just about anything that on the ground & they have a pouch in the head area that can collect all the unwanted toxin or polutant while ingesting food. But being CRS & CBS, thier pouch cannot release the subtance out from the body which being collect & once full it go into the body & the shrimp will die. As for baby shrimplet from born to 2 week, they only survive mainly on micro-bacteria & this pouch is not fully function. Since they like to stay where most planaria is, this make them the top target & will never survive any toxic that come into contact. Once dead it will mostly eaten by adult shrimp._
Comments!?
One thing I'm not clear on is if Planaria have a toxin on their surface wouldn't they be able to drive shrimp away in the last video?


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## dougolasjr (Mar 3, 2010)

greenman857 said:


> I am sure the shrimp attacked the Planaria, I've researched them enough to recognize them. and I'm certainly not saying that Planaria won't attack shrimp but, I guess I felt I wanted to clarify that Planaria aren't voracious shrimp killers that have to be eliminated.
> Possible thoughts
> 1) I have Malawa maybe they don't have the same sensitivity as the Neocards?
> 2) there is species differences in Planaria as to aggressiveness etc.
> ...



http://www.shrimpnow.com/forums/showthread.php/5607-planarias


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## greenman857 (Feb 25, 2012)

Ok to clarify or maybe summarize:
Planaria, can and will attack shrimp, when, how and why is subject to debate.
I think most would agree that:
_Planaria are not a serious threat to shrimp and do not have to be eliminated. The population density of the Planaria as well as your desired degree of shrimp production may encourage one to medicate to eliminate Planaria, but Planaria in a shrimp tank are not cause for serious alarm. In fact Planaria and shrimp can coexist in a tank for months, possibly years._
Comments?


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## mordalphus (Jun 23, 2010)

greenman857 said:


> Ok to clarify or maybe summarize:
> Planaria, can and will attack shrimp, when, how and why is subject to debate.
> I think most would agree that:
> _Planaria are not a serious threat to shrimp and do not have to be eliminated. The population density of the Planaria as well as your desired degree of shrimp production may encourage one to medicate to eliminate Planaria, but Planaria in a shrimp tank are not cause for serious alarm. In fact Planaria and shrimp can coexist in a tank for months, possibly years._
> Comments?


The same can be said about keeping shrimp with fish. It depends on what is more important to you, the stress levels and safety of your shrimp, or the existence of a nuisance animal in your aquarium. The treatment is cheap, easy and harmless to shrimp, so there is no downside to eliminating the threat.

I suppose it's all relative to your opinions though, because while losing a shrimp every once in a while may not 'cause serious alarm' for one person, for another person it could be a disaster. I prefer to keep my shrimp safe from any potential harm (at least the ones I can control), that's why I keep them away from fish, and I change their water weekly, and I feed them food, keep their water at a specific temperature, etc. The pest control simply is another part of their life I can control.


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## GeToChKn (Apr 15, 2011)

greenman857 said:


> Ok to clarify or maybe summarize:
> Planaria, can and will attack shrimp, when, how and why is subject to debate.
> I think most would agree that:
> _Planaria are not a serious threat to shrimp and do not have to be eliminated. The population density of the Planaria as well as your desired degree of shrimp production may encourage one to medicate to eliminate Planaria, but Planaria in a shrimp tank are not cause for serious alarm. In fact Planaria and shrimp can coexist in a tank for months, possibly years._
> Comments?


Loose a 50 cent low grade cherry shrimp to a planaria now and again, sure no big deal.

Loose a $500 PRL or Pinto TB and I bet you would hate planaria as you watch a berried female carrying $10,000 in eggs get killed by a planaria.


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## Calmia22 (Aug 20, 2011)

My shrimp typically eat any planaria before they get big. I might see little 1/4" worms, then as the shrimp scavenge for food they find them and eat them.


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## Soothing Shrimp (Nov 9, 2011)

GeToChKn said:


> Loose a 50 cent low grade cherry shrimp to a planaria now and again, sure no big deal.
> 
> Loose a $500 PRL or Pinto TB and I bet you would hate planaria as you watch a berried female carrying $10,000 in eggs get killed by a planaria.


+10,000 :icon_eek:


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