Macrobrachium sp. (Chameleon Shrimp)

Mr. Mom

Candiru
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Back in September I picked up 4 of these things, unknowing at first how aggressive they would be, and last month increasing to 7 in a 29G (5 males and 2 females). They kept me quite entertained over the past few months. Bold little creatures. They're in a community tank with some Tetras, Corydoras, Nerite Snails and an African Dwarf Frog. Up till now haven't lost any fish per say, although they do try. And a month ago added 2 cherry shrimp to kinda test the waters (they're still alive). But the tank doesn't lack hiding places.
Like the literature I've read on these creatures, I rarely see the females ... and most activity happens at night. They all have their own cave/corner/nitch to hide in, including the females.
I'd say so far the highlights of watching these guys in action would be the time I watched one male grab a Red Serpae by the tail and laid it flat to the tank bottom (fish got away). The other would be when another male decided to grab a corydora and got dragged part way across the tank before letting go.
Anyhow when I first got these guys I was curious about compatibility with nerite snails. They've been together since the end of September with no major issues. I'd see the Macro's pester the Nerites once in awhile ... but nothing came of it/no snails perished. Until a of couple days ago.
I noticed a Nerite let go of some wood and float to the bottom landing on its back (happens quite often and sometimes comical to watch them right themselves). Figured I'd continue with what I was doing and check on the show later.
Big mistake, these Macro's are opportunistic it turns out
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Came back to see this male Macro. killing my Nerite. (The Nerites are about the only tank mates I don't want to lose in this tank ... guess they'll be moving). So went to find my camera, by the time I got back the Nerite was dead and becoming dinner.
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An older pic of one that's a little more clearer. These guys do change color with their environment. When I picked up the 3 males back in November, they had a lot of blue to their bodies (whereas mine 4 at home had more red) before a day had past the 3 males were becoming more red in my tank. It all depends on their surroundings.
Back in September I was skeptical if these were in fact Chameleon Shrimp, but now I'm thinking I wasn't duped so to speak.

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Fat Homer

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^ As i commented back in your old thread, i'm pretty sure i had kept the same species or similar species before... and yeah, they definitely will pick and eat at anything they can grab... infact, i'm pretty sure i lost a few snails in the past to them, since i'd see them sending their long pincers down into the shells pulling out little bits of meat...

So anyway, are yours multiplying by any chance? since i never worked out if they could actually breed in freshwater, since i heard they need brackish for that...
 

Mr. Mom

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Hey Fat Homer ... actually when I watched the one nerite die, I thought of you and what we'd discussed. I remember you weren't 100% on it, so I was testing the waters so to speak ... things looked good .... turns out I was wrong (and the only thing I didn't want to lose in that tank). Haven't seen any multiplying as of yet, but I'll probably be making it more a species only tank. For all I know they may have bred and the few tetras in there ate them.
Been doing lots of reading on these guys when I can find the info. Found some stuff that says brackish water is needed, but most other literature says they'll reproduce in freshwater ... conflicting.
Meanwhile i've read that the females will disappear to guard the eggs ... well they've done that a number of times now - disappear for a week minimum. Although the few and brief times I see my 2 females, I've never noticed any eggs ... so some changes are needed. To be honest, I've lost all interest in my Cherry Shrimp because of these Macros. To the point this will probably become my first species only tank. (It's never appealed to me before - species only).
So guess its time for some changes and then let things be ... so we can see what happens.
 

Fat Homer

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^ might be an interesting project to try out, especially if you could somehow manage to breed them...

In the past when i've bought a bunch of these shrimp / prawns, there have been at times 1 pregnant female, but just like you, never actually saw any fry...


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Mr. Mom

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Well these guys were fun while it lasted. I had picked up a few more (2 big males as well) but nothing exciting to report after it all. I eventually moved the Tetras out of the tank. Then added some White Mountain Minnows, never did see the Macros catch anything.
I did see one of the females carrying eggs once, but never saw anything come from that either.
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This guy though slowly and methodically hunted down every one of the Macros until there was just the 2 big males and 1 female. Then the female eventually died (appeared to be a casualty from the 2 males fighting) and the one male was missing his arms, he died soon afterwards. Then I was left with just this guy. Thought about getting more, but decided I was done.
My last male passed away 2 nights ago ... it was 2" long at that point. The photo was taken a month or two back.

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