# Hydras and planaria drama in cherry shrimp tank (and the use of liquid fenbendazole)



## prawnetheus (Sep 16, 2014)

Howdy everyone, shrimp newbie and first-time poster here. The information on this forum has been so helpful to us, my hubby and I would like to contribute our observations as well.

Problem:
We have a 6 gal tank (0 ammonia, 0 nitrite, 10-20 nitrate, 6.4 pH) with cherry shrimp, babies, and lots of bladder and ramhorn snails. The tank was infested with planaria and hydra. The pests most likely came from the plants we got from the store. *As the planaria number and physical size increased, we noticed a sharp decrease in the number of baby shrimp and snails.*

Mystery:
I know that many people say hydras and planaria can be controlled by feeding less, but this tank has only been fed in tiny amounts for a total of 3-4 times in the 6 weeks it has been operational. It does, however, have a lot of algae. We were puzzled as to what was causing the planaria population to explode in numbers and baby shrimp and snail population to shrink. *We hypothesized that the large ones were preying on the baby shrimp and baby snails, which were feeding on the excessive algae growth and biofilm. The algae and biofilm are probably also the baby planaria's food source.* We dropped 2 amano shrimp in the tank for a few days hoping they would control the algae, but they acted so miserably that we moved them to another tank. We don't know why they were so stressed out.

Hydra/shrimp/snail interaction:
From what we could see on the sides of the tank, we had about 10-15 hydras. We've never seen the hydras catching anything; however, we did notice that the adult cherries would occasionally swim around the tank looking distressed. Also, when brushing against the hydras they would dart away. 

Planaria/shrimp/snail interaction:
We saw about 8 large planaria and countless little ones in the tank. Many people believe that planaria eat detritus and are harmless, but I'm starting to think that it may be species-dependent, as mentioned in this site. I witnessed a 10 mm long planaria (all of ours are the white variety) moving on the glass waving its head left and right, and upon contact with a baby snail it quickly grabbed it with its mouth and wrapped itself around it. In less than 10 minutes, all that was left over was a little bit of the shell. *This type of white planaria is definitely predatory when they're big, and they definitely have the capacity to take down a baby shrimp (which is most likely what happened to our baby shrimp and snail population).*

Liquid fenbendazole solution:
We decided to use fenbendazole to eradicate the pests. Here's some preliminary information as to its effects on shrimp, snails, and the pests: Going off of this thread, we've dosed our tank with 15 mg of liquid fenbendazole at 2.5 mg/gal (2.5 mg * 6 gal = 15 mg). The product is listed 



. It contains 100 mg/ml of the compound, so we administered 0.15 ml of the product. We did not change the water for 3 days after dosing, and the filter was left on.

Day 3 pest status:
There are no more hydras. We saw what MIGHT be one shriveled up stalk, but that could've easily been something else. We saw tons of what seemed like dead planaria under the substrate, and we spotted one moving around. It looked very odd in that it was not elongated at all but rather short and fat. It was barely able to stay on the glass and fell off onto the substrate. 

Day 3 shrimp and snail status:
All the non-berried adult cherries were out and grazing normally, none of the babies were spotted prior to dosing fenbendazole, so we're just assuming that they have been eaten by the planaria. The single berried female looked fine and still had her eggs, but wasn't the calmest. Even the tiniest snails are alive; however, that's not to say that none of the snails have died because we don't keep track of how many snails there are in our tank.

We did a 15% water change and redosed with the same amount of fenbendazole. We're waiting 3 more days. I'll be posting some more updates soon!

Hope this is helpful to anyone encountering these nasty things!


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## greaser84 (Feb 2, 2014)

Good info. I've had to treat for Planaria as well, pretty much the same thing you did, with no shrimp loss. I agree 100% that overfeeding is not the only cause.

Bump: Good info. I've had to treat for Planaria as well, pretty much the same thing you did, with no shrimp loss. I agree 100% that overfeeding is not the only cause.


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## lamiskool (Jul 1, 2011)

greaser84 said:


> Good info. I've had to treat for Planaria as well, pretty much the same thing you did, with no shrimp loss. I agree 100% that overfeeding is not the only cause.
> 
> Bump: Good info. I've had to treat for Planaria as well, pretty much the same thing you did, with no shrimp loss. I agree 100% that overfeeding is not the only cause.


also gunna have to agree, there are tanks I have that I never feed and still find em


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## greaser84 (Feb 2, 2014)

lamiskool said:


> also gunna have to agree, there are tanks I have that I never feed and still find em


Yep it's the same with snails. My biggest Snail populations are in shrimp tanks I never feed. If the shrimp can survive and breeding without any food being added so can every aquarium pest unfortunately.


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## cjstl (Mar 4, 2013)

I wonder if very small planaria can kill baby shrimp. I purchased two berried orange sakuras a few weeks ago and put them in a 1G cube. One of them gave birth several days ago. I initially saw tons of little shrimplets, but now I find it a lot harder to spot them. I haven't seen any large planaria in the tank, but I have seen some small ones, and the number has been increasing in the last few days. They're also out crawling on the glass during the day, as if they're hunting. I may grab some fenben myself, because I really want to keep these shrimplets alive.


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## Tyveck (Jul 6, 2014)

I was having this same problem in my shrimp tank! I wasn't over feeding or anything. They just kept coming! I'm pretty sure they came off some moss I ordered... Anyway you don't normally see them in a community tank because fish love to eat them! So what I did was purchased 3 CPD fish. I put them in there and within 4 day no hydra or planaria! I decided to keep these little cute fish in my shrimp tank just because they were doing such a great job keeping the tank free of nasty things. The have never bothered any of the 65+ shrimp in my tank either. I do a head count everyday and I have never lost one including babies! I would encourage all shrimp owners to put a couple female cpd or 1 male and 2 females in your shrimp tank. They have earned their keep in mine! I know some people say there are no safe fish to keep in your shrimp tank, but I have found different 3 months later and not a single planaria or hyrda in my tank and I haven't lost any shrimp or baby shrimp!


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## Kato (Oct 13, 2011)

Tyveck said:


> I was having this same problem in my shrimp tank! I wasn't over feeding or anything. They just kept coming! I'm pretty sure they came off some moss I ordered... Anyway you don't normally see them in a community tank because fish love to eat them! So what I did was purchased 3 CPD fish. I put them in there and within 4 day no hydra or planaria! I decided to keep these little cute fish in my shrimp tank just because they were doing such a great job keeping the tank free of nasty things. The have never bothered any of the 65+ shrimp in my tank either. I do a head count everyday and I have never lost one including babies! I would encourage all shrimp owners to put a couple female cpd or 1 male and 2 females in your shrimp tank. They have earned their keep in mine! I know some people say there are no safe fish to keep in your shrimp tank, but I have found different 3 months later and not a single planaria or hyrda in my tank and I haven't lost any shrimp or baby shrimp!


What is the reason for 1 male and 2 females?


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## prawnetheus (Sep 16, 2014)

cjstl said:


> I wonder if very small planaria can kill baby shrimp. I purchased two berried orange sakuras a few weeks ago and put them in a 1G cube. One of them gave birth several days ago. I initially saw tons of little shrimplets, but now I find it a lot harder to spot them. I haven't seen any large planaria in the tank, but I have seen some small ones, and the number has been increasing in the last few days. They're also out crawling on the glass during the day, as if they're hunting. I may grab some fenben myself, because I really want to keep these shrimplets alive.


Hmm... I don't think the very small planaria will kill baby shrimp. I forgot to mention another observation of a large planaria (~7 mm) coming in contact with a ~3 mm bladder snail and immediately turning away. Whereas the largest planaria (~10 mm) I saw attacking and eating the baby bladder snail (~1.5 mm) immediately latched on. There might be some sort of a size detection threshold for whatever sensory organs they are using to probe their environment for food, which would make sense that they don't attempt to attack something too big that can potentially be its own predator.

I tend to see the tiny planaria hanging out on the glass where lots of algae and biofilm are growing. My guess is that when they're small, their food source are comprised of the same materials other tiny organisms eat. As they get bigger, they may prey on daphnia and eventually attack things that are 1.5 mm in size (baby snails, the head or tail of a baby shrimp).



Tyveck said:


> I was having this same problem in my shrimp tank! I wasn't over feeding or anything. They just kept coming! I'm pretty sure they came off some moss I ordered... Anyway you don't normally see them in a community tank because fish love to eat them! So what I did was purchased 3 CPD fish. I put them in there and within 4 day no hydra or planaria! I decided to keep these little cute fish in my shrimp tank just because they were doing such a great job keeping the tank free of nasty things. The have never bothered any of the 65+ shrimp in my tank either. I do a head count everyday and I have never lost one including babies! I would encourage all shrimp owners to put a couple female cpd or 1 male and 2 females in your shrimp tank. They have earned their keep in mine! I know some people say there are no safe fish to keep in your shrimp tank, but I have found different 3 months later and not a single planaria or hyrda in my tank and I haven't lost any shrimp or baby shrimp!


That's a great idea! I'm glad they worked so well for you. We were considering adding a few of the smaller rosy red minnows from our fountain to the tank, but they seemed so movement-driven that I didn't think they would even notice the clear, slow-moving planaria. We decided on the F-bomb instead.

Only after finding planaria in our 6 gal shrimp tank did we notice tons of tiny planaria in our other 15 gal tank with 4 filter shrimp, 7 kuhli loaches, 5 ghost shrimp, an gold inca snail and a nerite snail. The interesting thing is that these planaria are really small and tend to cluster higher up on the walls of the aquarium. We've never seen a large planaria in this tank which has been in operational twice as long as the 6 gal shrimp tank has.

There might be 3 explanations for this: 
1. As soon as the planaria got to be a decent size, either the loaches or ghost shrimp detect and ate them. 
2. The big inca and nerite snails and the filter shrimp are keeping algae and biofilm growth under control and limiting the food source of baby planaria.
3. Planaria population are just beginning to increase and will eventually get out of control. (I hope it's not this one!)


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## Tyveck (Jul 6, 2014)

The reason for the male and two females is just help the fish school and feel more comfortable in your tank. They are schooling fish and the males can be territorial to each other. Females will be playfully chased all the time by the male. It adds quite the show and excitement to your tank!


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