# Hydra - should I be worried?



## Dr Mike Oxgreen (21 Jan 2016)

Not sure if I've put this in the right part of the forums - mods, please move it if you think there's a better place for it!

Whilst sharing the following picture of my HC 'oxygen factory', I noticed the illegal immigrant. Look about a third of the way down the picture, about a fifth of the way in from the left - the whitish tubular thing with tentacles. It's a hydra!






And now I'm seeing several of them. One has tentacles nearly half an inch long. In fact I think there are at least two more rather out-of-focus in the picture: one near the top left and another near the top right. They seem to like attaching themselves to the HC and also to the glossostigma - do they like the oxygen-saturated water?

Do I need to be worried? The tank is a 25 litre nano, with 7 chili rasboras, 3 otocinclus and some blue velvet neocaridina shrimp (not sure how many, and they're dying off one by one, which is another story).

My guess is that they might threaten baby shrimp if I get any, but probably won't manage to catch adults. I also guess that adult shrimp will be immune to the sting due to their shells. The chili rasboras are probably too big to be caught, but might they be stung and harmed?

I have tried squirting a tiny amount (1 ml) of 3% hydrogen peroxide at them, but this had no effect at all.

If they're likely to be harmless to my other inmates then I'm happy to leave them as a fascinating addition to the tank.


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## zozo (21 Jan 2016)

They are predatory, they eat, cyclops and such little additional life forms in your tank. Indeed shrimp fry is also ammong it's victims. They reproduce with laying eggs and also can regenerate by division like a wurm if cut in half..  If you feed alot with for example daphnia, you could stop that for a while and they could reduce in numbers.. Natural enimies of the hydra are Mollys and plattys, gourami and sticklebacks.

In a nano tank a few stickleback are not to big and a funny addition. The also do not live such a long life.. Indoors in warmer tanks maybe 1 year or less.. So it's a perfect little temporary hydra terminator..


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## Tim Harrison (21 Jan 2016)

There's one top left as well, and in the right hand quadrant - out of focus...they'll be load more lurking elsewhere. eSHa Gastropex will kill these 'orrible nasties...http://www.eshalabs.eu/europe/products/esha-gastropex.html
Failing that contact the Marvel Universe and ask Shield to help...Hail Hydra


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## PARAGUAY (21 Jan 2016)

I thought I had read Hydra beware with a Gourami,but did not know Platies ate the blighters,nice info zozo


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## dw1305 (22 Jan 2016)

Hi all,





Troi said:


> eSHa Gastropex will kill these


<"Panacur"> (Fenbendazole) works as well.

cheers Darrel


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## Dr Mike Oxgreen (22 Jan 2016)

Great, thanks. If the problem gets any worse I'll try one of those.


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## zozo (22 Jan 2016)

PARAGUAY said:


> I thought I had read Hydra beware with a Gourami,but did not know Platies ate the blighters,nice info zozo



Thanks  i never experienced it first hand with molly, platy or gourami, never had hydra in my tanks i also got it from another biology site about water life.
Stickleback i had alot in my tanks when i was a kid, caught them with a net in the nearby swamp.. They are the most fearless little predators i've ever seen they eat a lot that moves around. Recently did read a study that sticklebacks even like to live around shrimps, not to feed on them, the reason for this behaivor is unclear. But the researchers always found schools of shrimps and stickleback together in large amounts. They did some tests as well, but seem they just like to coexist.. 

Next spring when they are available again at the lfs i'll get a few, to find out if they also eat planaria.. Got some of them in the tank..


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