# Hydra maybe? Pictures.



## Keri (Aug 2, 2010)

Tank is a very well established 65g community planted. The area in question is a breeder sattelite box that I have set up for 2 baby dwarf parrots. I've been noticing little microorganisms on the inside of the plastic box moving around a bit, primarily a couple that look like hydra (#1), they retract, a few sort of "starry" shaped things that don't appear to move (#2) and some mobile nematodes (arrows).

Sorry for the picture quality my camera was hating me for trying to focus on these tiny things with no macro lens. Even the "hydra" thing can't be more than 1 or 2 mm.

So I guess my questions are:
1) Is this a hydra, and if so, will it harm the baby fish?
2) Any clue on the "starry" shapes?
3) Do you think the nematodes are harmful, or are they just treating the breeder box like a refugium? I saw one of the baby fish try to eat one but it was unsuccessful.

Group photo:









Crop:


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## Ursus sapien (Apr 21, 2010)

green hydra (Hydra viridis) not a serious threat except to copepods, paramecia and daphnia. They're not especially good at catching free-swimming fish fry or shrimp paast the first molt -the threat is hugely over rated. They tend to die out when the copepods, paramecia and daphnia are exhausted.


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## Keri (Aug 2, 2010)

Ursus sapien said:


> green hydra (Hydra viridis) not a serious threat except to copepods, paramecia and daphnia. They're not especially good at catching free-swimming fish fry or shrimp paast the first molt -the threat is hugely over rated. They tend to die out when the copepods, paramecia and daphnia are exhausted.


Thanks Storm, they are welcome to do their thing in my tank so long as it doesn't hurt the baby fish (which are 2x their length and outweigh them enormously I'm sure) I'll take their being there as a good sign that there are lots of micro fauna in there for the babies to eat in addition to the food I feed them


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## Ursus sapien (Apr 21, 2010)

Keri, I did neglect to mention that: 1) hydra can sting the babies (they are related to jellyfish, after all) but when I had them in the heterandria tank the fish learned to avoid them; 2) hydra do not die of old age - they're essentialy immortal in that regard; 3) if you break up a hydra, the bits can _all _regenerae into new hydra (just like planaria!) so if you try to remove them, do it carefully; and 4) if you get fed up with the hydra, get some spixi snails - they eat them (yum).


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## Keri (Aug 2, 2010)

Hmmm... I think the babies will learn to avoid but it's not a huge area in the breeder box. Do you happen to have spixi snails? (only if there is something else I can feed the snails when they are done though, I wouldn't want them to starve after all the hydra are gone)


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## Ursus sapien (Apr 21, 2010)

If you're worried, try using a large pipette or turkey baster to remove the hydra. I'm hoping to get spixis when shipping weather commences (they've been hard to find, probably because they eat plants). If I do get them, I'll offer them out as 'loaners' for people with hydra or planaria issues The planaria eating is a rumour, but I'd like to test it.


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## Keri (Aug 2, 2010)

Well I almost feel bad killing something that lives forever lol!


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## Keri (Aug 2, 2010)

These are the babies (probably 20x life size haha)


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