# macrobrachium ghost shrimp?



## smilla (Dec 13, 2003)

I was wondering if all macrobrachium are considered aggressive. Or do they become aggressive upon reaching a certain size?

I do not know which kind of ghost shrimp I have. I know it's a she, because she has carried eggs. She's approx 1.25 inches long, clear, and has red bands on her "wrists", and at the base of her antennae. Actually they were red once, but now have turned yellow. ( I don't know if this is related to what she is eating - she used to get flake food, now she gets algae tablets ) . She is covered with yellow spots and has a single yellow dot at each corner of her tail.

She doesn't seem to bother the fish (which are all approx 1-1.5in, with the exception of the betta). But if they get in her way she's not afraid to threaten them with her claws.

How do you tell the difference between the "ordinary" ghost shrimp and the macrobrachium when they're this small (or smaller)?

I have heard that macrobrachium can get to be 4+ inches long, and I don't know what I would do with her if she were to get larger and more aggressive. I'm hoping she has reached maximum size...


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## Veneer (Jan 18, 2005)

You really can't tell the difference between ghost shrimp and young _Macrobrachium_; seeing how your particular shrimp was observed egg-laden, it is most likely fully mature and should not grow any larger (regardless of classification).

_Macrobrachium_ is the largest genus of the Palaemonidae (200+ species); it is hard to generalize across their breadth (in regard to your "four-inch" length concerns); there are some extremely peaceful and small substrate-burrowers and water-column swimmers (as "Indian pearl/sand shrimp" - see www.petshrimp.com - a spectacular site for information and discussion - under the heading of 'Shrimp Varieties' and scroll down to "detritus-eaters") and then... Well, I'll let the following image speak for itself.

http://www.aqua-addiction.com/forums/index.php?act=Attach&type=post&id=24468


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## Aphyosemion (Oct 15, 2004)

It has seemed to be my observation that ghost shrimp in general get those tiny little red bands on their claws and antennae when they are fully mature. I have many ghost shrimp with those markings and they seem to be, without exception the larger specimens. I'm not exactly sure what the difference is between the saltwater variety and the true freshwater variety though, or how long the saltwater variety can live in freshwater. That is the only thing that makes me a little uncertain whether what I have are the regular freshwater ghost shrimp. Assuming they are, it seems to be normal for them to get those colorations when mature.
It is unlikely that you would get baby machrobrachium shrimp mixed up with fully grown ghost shrimp. Not only would the LFS have to mix them in together and mistakenly sell them very cheap, but you would probably see noticeable diffferences between the machrobrachium species and the other ghost shrimp in your tank.
-Aphyosemion


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## Veneer (Jan 18, 2005)

It is actually not that rare for young _Macrobrachium_ to turn up in shipments of ghost shrimp- I personally own a specimen sold as such; the vagaries of wild collection and wholesale facilities generally account for this mixup. Young _Macrobrachium_ (and the adults of numerous Neotropical and southern/Southeast Asian forms fall, in the occasions that they appear in market, under the heading of "Indian ghost shrimp" or the like.

See http://www.g-hoener.de/images/19 Andere Aquarientiere/Macrobrachium_lamerrii.JPG for an illustration of "first-glance" similarity (at "small ghost-shrimp" size, the disproportionate length of the from limbs is greatly reduced).


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## Aphyosemion (Oct 15, 2004)

Hmm....very interesting. I can see where the mixup could happen in a species with a close resemblance to ghost shrimp, such as the one you showed. I think the diffferences between that shrimp and a ghost shrimp would be apparent long before it reached 10 feet in length and began eating your dogs and cats, though. Even by the time it reached, say, 2" in length, the longer arms would be apparent, as well as any differences in markings and the probably lack of the "hump" seen in ghost shrimp. The point I am trying to make is that you would be able to realize it wasn't a ghost shrimp before it started eating your fish, so there is no need to panic.
-Aphyosemion


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## Veneer (Jan 18, 2005)

Aphyosemion said:


> The point I am trying to make is that you would be able to realize it wasn't a ghost shrimp before it started eating your fish, so there is no need to panic.


It has happened (mostly due to ignorance or the assumption that what one has is merely a "large ghost shrimp"); these experiences, when publicized give "ghosties" unwarranted negative press.

That being said, even ghost-shrimp-sized _Macrobrachium_ have been known to nip at fish (even those much larger than themselves) unbeknownst to the aquarist, leaving them to puzzle over a slew of mystery injuries and remove potential piscine aggressors before suspecting the shrimp (which are often outwardly quite timid).


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## Aphyosemion (Oct 15, 2004)

I'm sure it's possible. I've had Macrobrachium shrimp that were about 3" long plus long arms and didn't harm any of my fish, though. You never know when they could just discover your fish are a tasty snack and go wild, but at least when they're the size of ghost shrimp, they aren't likely to bring down most fish, even if they tried.
-Aphyosemion


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## snake (Jan 11, 2005)

When I started my nano, it had only 3 ghost/ glass from the discus tank in it.
So when I added the pygmy cories(told the LFS guy to pick out the bigger ones,arrived too early,he was a Butt) the one Tiny/baby was attacked immediatly by one of the shrimp. I had to free him two different times before I got the ninja shrimp back into the big tank. BTW, I added appr 3 dozen ghost to my Discus tank months ago after i was unable to find sizable Amanos and now I believe the blasted things are breeding. When ever I vacumn, i suck up very tiny ones, very few since I suspect the loaches maybe snacking on some. Its funny to see a 1 inch shrimp "bow up" to a 4inch juvi discus over a miniscule floating food particle. He, he, not for long

Dean


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## Veneer (Jan 18, 2005)

How large was the aggressive ghost shrimp in relation to the fish?


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## Aphyosemion (Oct 15, 2004)

Yeah, I have had ghost shrimp eat baby guppies, but they seem to leave anything larger than freshly born fry alone. I have also heard that they become more aggressive in higher temperatures. Mine are mostly in unheated tanks.
-Aphyosemion


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