# Noticed Hydras in my tank



## Monster Fish (Mar 15, 2011)

res34 said:


> I noticed what appear to be a few hydras in my 10 gallon planted aquarium. Should I be worried about them?
> 
> In my tank are 3 otos, 2 assassin snails, plenty of bladder snails (also called pond snails), and a mystery snail I just bought today (to take care of brown leaves and such). I plan on getting cherry shrimp eventually. Will any of these (save the oto) eat/control these? Are any of them at risk?


They'll eat your cherry shrimp. Grab a package of fenbendazole (dog dewormer) from Petsmart/Petco and dose 0.1 grams per 10 gallons of water for 3 doses with 48 hours between each dose. IME, it doesn't harm pond/bladder snails but I'm not sure about the assassins or mystery snails. I'd take them out during the treatment to be safe.


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## res34 (Mar 23, 2013)

Do they only harm shrimplets or would the adults be in danger. I've also heard of some mention of mystery snails and assassin snails eating hydras, but can't seem to confirm it or not.

I also have access to a tank with guppies, platies, and mollies. I know that they tend to be literally "picky" eaters (always scrounging for food regardless of how many feedings). Would moving one of these over to the tank decimate the hydra (I only see 4 or 5)?


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## inthepacific (Oct 21, 2012)

just get a fine net and net them out.


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## Monster Fish (Mar 15, 2011)

res34 said:


> Do they only harm shrimplets or would the adults be in danger. I've also heard of some mention of mystery snails and assassin snails eating hydras, but can't seem to confirm it or not.
> 
> I also have access to a tank with guppies, platies, and mollies. I know that they tend to be literally "picky" eaters (always scrounging for food regardless of how many feedings). Would moving one of these over to the tank decimate the hydra (I only see 4 or 5)?


They eat shrimplets and they can sting your adults causing unwanted stress. The only snails that will eat them are spixi snails and those are difficult to find.

They might eat at the hydra (not too sure) but they are often too small to be noticed by fish. My microrasboras didn't touch them. If you see 4 or 5, there's definitely more lurking around the tank.


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## Oceangirl (Feb 5, 2013)

I heard mollies eat hydra, but they also eat plants too. I'd plop one in and don't feed it. It will supposedly decimate the hydra population.


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## res34 (Mar 23, 2013)

I'm hoping one of the snails and/or fish can eat them, as the dewormer mentioned by Monster Fish will likely kill the mystery and assassin snails, according to google searches. I'll probably try the guppies first (there are two of them, both male) and see if they can handle it. That or I could use this as an excuse to buy some nano fish for the tank to control them, though I can't think of any that wont go after shrimplets.


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## MsNemoShrimp (Apr 25, 2011)

Do all hydras eventually get big? I had some in the past but the biggest I've seen them is about the size of this - so not sure how they could eat shrimps?


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## res34 (Mar 23, 2013)

I think they eat the shrimplets, which are pretty small.


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## Monster Fish (Mar 15, 2011)

res34 said:


> I'm hoping one of the snails and/or fish can eat them, as the dewormer mentioned by Monster Fish will likely kill the mystery and assassin snails, according to google searches. I'll probably try the guppies first (there are two of them, both male) and see if they can handle it. That or I could use this as an excuse to buy some nano fish for the tank to control them, though I can't think of any that wont go after shrimplets.


Remove the assassins and mystery snail during the week long dosing then do a few water changes afterwards and use some activated carbon. Then it should be safe to add them back into the tank.




MsNemoShrimp said:


> Do all hydras eventually get big? I had some in the past but the biggest I've seen them is about the size of this - so not sure how they could eat shrimps?


I've had hydra that were upto 1cm long. They were all over my plants and the front glass. The tank didn't have any shrimp at the time so I nuked the tank with fenbendazole.


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## CookieM (Feb 7, 2012)

After using fenbendazole. Any introduction of snail will kill off that snail. I did like 8 water changes already after using fenbendazole a month ago and it still kill my nerite even when I acclimate it.


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## Oceangirl (Feb 5, 2013)

Add the molly, They eat anything when hungry. Also Celestial pearl Danios or Galaxy rasboras are nano fish that leave your shrimp alone.


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## res34 (Mar 23, 2013)

Thanks for the advice, I'll add one when I have free time to observe (just to make sure it doesn't harass anything else in the tank, though I doubt it, as well as to make sure it does ok after the transfer).


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## MABJ (Mar 30, 2012)

They'll eat anything including shrimp.

Dose fenbenzonole. 

I've found the only snail affected is nerite. I dose with all 'pest' snails and their populations don't suffer.


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## res34 (Mar 23, 2013)

Well I don't have the shrimp yet, so I might go with the molly just for now. As for the fenbenzonole, I've done a few google searches and heard that while pest snails can resist it, "higher" snails like nerites and assassins are very vulnerable. Not sure why though.


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