# Hydra color



## Red_Rose (Mar 18, 2007)

Hello,

I have some hydra in my betta's tank and I had noticed that they are a green color. I've only ever seen white ones.

Is there any difference between white and green hydra aside from their color?

Thanks.


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## HeyPK (Jan 23, 2004)

There is the green hydra which has symbiotic (mutualistic) algae called zoochlorellae. And then there is the somewhat larger brown hydra which does not have zoochlorellae.


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## Shrimp (Jun 1, 2010)

HeyPK said:


> There is the green hydra which has symbiotic (mutualistic) algae called zoochlorellae. And then there is the somewhat larger brown hydra which does not have zoochlorellae.


Yup!


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## Red_Rose (Mar 18, 2007)

So is one better then the other? I heard that the brown(I've heard it called white) hydra appear when a tank is dirty. When I had a lot of mulm build up in my guppy tank, I noticed a lot of little white hydra about. This is the first time I've ever had green ones in a tank.


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## HeyPK (Jan 23, 2004)

The brown hydra really are kind of brown. They are also larger than the green ones. Are you sure that the white things you saw in the guppy tank were hydra? The brown ones think they are better than the green ones because they are bigger, but the green ones think they are better because they can get part of their food from the symbiotic zoochlorellae. Actually, I would rather have neither of them in my tanks.


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## Red_Rose (Mar 18, 2007)

It was definitely hydra in that tank. I've seen many different little critters in my tanks and those are ones that I can never mistaken. They could have very well been green but they looked white to me. They looked a bit bigger then the ones in my betta's tank.

My tanks are NPT's so I think having such things in there are normal. If I were going to raise fry then I would definitely want them out of there!


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## fishyerik (Oct 8, 2008)

There's a lot of Hydra species, see: http://en.wikipedia.org/wiki/Hydra_(genus)

Even in the same species there can be different colors, for example green Hydra can live without the mutualistic algae, and then it's not green.


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## Red_Rose (Mar 18, 2007)

fishyerik said:


> There's a lot of Hydra species, see: http://en.wikipedia.org/wiki/Hydra_(genus)
> 
> Even in the same species there can be different colors, for example green Hydra can live without the mutualistic algae, and then it's not green.


Thanks for that link.  I bookmarked it for future reference.


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