# Mud Crabs Have Arrived ,Rropanopeus harrisii, Now with Eggs



## dougolasjr (Mar 3, 2010)

So I got the order for what were called Mud crabs in today. I actually got sent 1 extra so I have 5 instead of 4 which is a nice surprise. Taking pictures later tonight.


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## Rob in Puyallup (Jul 2, 2009)

Looking forward to pics! 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## ADJAquariums (Jul 5, 2012)

I can't wait to see them!


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## rainbuilder (Sep 21, 2011)

My friend catches those in a lake near here. They're the small brackish/freshwater ones that start with an r, right?


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## dougolasjr (Mar 3, 2010)

rainbuilder said:


> My friend catches those in a lake near here. They're the small brackish/freshwater ones that start with an r, right?



I believe that's what they are.   _Rhithropanopeus harrisii _


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## Geniusdudekiran (Dec 6, 2010)

Are they fine in freshwater? I'm excited!


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## hydrophyte (Mar 1, 2009)

Those are so interesting. I would be interested to know more about them.


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## rainbuilder (Sep 21, 2011)

That's them! She has actually kept some in her tank and had some that were kind of blue in color. Good luck with them!


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## dougolasjr (Mar 3, 2010)

Geniusdudekiran said:


> Are they fine in freshwater? I'm excited!


They are in freshwater.


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## GreenBliss (Mar 7, 2012)

Awesome. I can't wait to see how they do in your tank. They look adorable. :icon_smil


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## dougolasjr (Mar 3, 2010)




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## MABJ (Mar 30, 2012)

Yes, yes, yes, yes, yes. Thanks so much for sending me this link  

These are so neat. I'll be looking forward to updates )

How big are they, what tank are you keeping them in and have they been aggressive yet?


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## Rob in Puyallup (Jul 2, 2009)

Yeah, I've been wondering the same thing. Are they those teeny tiny crabs? 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## MABJ (Mar 30, 2012)

Rob in Puyallup said:


> Yeah, I've been wondering the same thing. Are they those teeny tiny crabs?
> 
> Sent from my Samsung Galaxy S III using Tapatalk 2


You might be thinking of the Thai Micro Crabs. They're fully fresh water. 

These are a different species we had a discussion on about a month ago. They're for sale on eBay. They are apparently a brackish water crab with adaptive freshwater capabilities.


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## Rob in Puyallup (Jul 2, 2009)

Must be extra hardy, seems they're taking over the whole world:

http://en.wikipedia.org/wiki/Rhithropanopeus_harrisii


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## MABJ (Mar 30, 2012)

Rob in Puyallup said:


> Must be extra hardy, seems they're taking over the whole world:
> 
> http://en.wikipedia.org/wiki/Rhithropanopeus_harrisii


Yup! That's them.


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## Sake (Mar 30, 2012)

Been waiting for these to arrive  subbed.


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## dougolasjr (Mar 3, 2010)

MABJ said:


> Yes, yes, yes, yes, yes. Thanks so much for sending me this link
> 
> These are so neat. I'll be looking forward to updates )
> 
> How big are they, what tank are you keeping them in and have they been aggressive yet?


I would say they are about 1 cm they have not been aggressive. They are in a tank with just snails so. The tank is a 10 gallon with lots of peacock moss. It was originally intended for Thai Micro Crabs but...


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## HX67 (Jul 15, 2010)

Hey, great! Thanks for this thread!

Ever since finding out this species is rapidly inhabiting The Baltic Ocean, I've been wanting to find and keep some.

Following along to see how they work for you.

A question: many crabs need/like emersing from water at times. Are you seeing any signs of this, or is it a true aquatic species, like most of the full marine crab species seem to be?


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## dougolasjr (Mar 3, 2010)

They mostly have been hanging out in the moss. I haven't had much time to watch them tho.


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## MABJ (Mar 30, 2012)

HX67 from what I read and what the seller tells me, they are fully aquatic. However, that doesn't necessarily mean they are.


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## HX67 (Jul 15, 2010)

MABJ said:


> HX67 from what I read and what the seller tells me, they are fully aquatic. However, that doesn't necessarily mean they are.


Indeed!
The plot thickens, somewhat.

Kid'n.

Just a parameter I'm interested in.
After having kept _Geosesarma_s, _Sesarma_s, _Uca_s, _Cardisoma_, _Gecarcinus_ and a couple of unidentified crabs and finding/getting several species of Full marine crabs in reef setups, I want to know more about them.

AND I'm finishing a setup suitable for semi-amphibious freshwater/brackish crabs, so further data on _R. harrisii_ is welcomed.


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## dougolasjr (Mar 3, 2010)

I have a big mass of banana plant leaves that sit at the top, and I have not see them make any move to try and leave the water.


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## dougolasjr (Mar 3, 2010)

More pics.


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## GreenBliss (Mar 7, 2012)

Love the last photo.


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## Geniusdudekiran (Dec 6, 2010)

Do they come up for air, or are they fully aquatic?


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## MABJ (Mar 30, 2012)

Geniusdudekiran said:


> Do they come up for air, or are they fully aquatic?


That was a question already in this thread. Lol two or three posts up he said he hadn't observed it. When I pmed the seller, he told me fully aquatic as well. Now that doesn't mean they are, but still.


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## MABJ (Mar 30, 2012)

dougolasjr said:


> More pics.


Really digging the pics. I'll be interested to hear your take on space requirements. Once they grow out and get their territory picked out, you should have a good feel for it.


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## dougolasjr (Mar 3, 2010)

Geniusdudekiran said:


> Do they come up for air, or are they fully aquatic?


I have not observed anything that would make me think they have any need to come up for air.


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## Geniusdudekiran (Dec 6, 2010)

MABJ said:


> That was a question already in this thread. Lol two or three posts up he said he hadn't observed it. When I pmed the seller, he told me fully aquatic as well. Now that doesn't mean they are, but still.


Oh, I see. But just because something leaves the water doesn't mean it's not fully aquatic -- Amano shrimp jump and crawl out of the water given the chance, but nobody can say they're non-aquatic lol. But I see what you're saying.


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## Vesh (Jan 16, 2010)

What do you feed them with? Do you think they will be ok with shrimps?

Thanks!


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## dougolasjr (Mar 3, 2010)

They are in a tank by themselves, except for some red/pink ramhorns snails. I have been feeding them, Somewhatshockeds (Jake), veggie sticks, strong, and complete veggie.


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## Betta Maniac (Dec 3, 2010)

They're so cute! Interested to see how this goes and big the end up getting.


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## dougolasjr (Mar 3, 2010)

From everything I have read they range from 20-26 mm.


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## dougolasjr (Mar 3, 2010)

Well as of tonight I did not see the crabs at all. I would assume they are just hiding. I put the moonlights on and after an hour or so I did see one of them. I put food in a glass dish hopefully they are able to climb in it to find the food and aren't afraid to do so.


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## MABJ (Mar 30, 2012)

I think they'll be ok hehe. I need to use a food fish >_<.


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## hydrophyte (Mar 1, 2009)

I have a tank where it would be fun to include these, but I bet they would kill fish.


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## AVN (Oct 3, 2012)

I'm waiting til you get them bred.

And for you to throw in some shrimp and see if they are aggressive.

Back to lurking.


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## dougolasjr (Mar 3, 2010)

Well between yesterday night and this morning I only saw a crab twice. Once when the lights were off last night and the moonlights were on. The other time was this morning when turning the lights back on. I would assume they are just hiding eating in the moss.


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## dougolasjr (Mar 3, 2010)

*Crab Tank*

So I only caught a glimpse of one crab this morning he was deep in peacock moss. The tank they are in is below.


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## GreenBliss (Mar 7, 2012)

I bet they love that tank.


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## Sake (Mar 30, 2012)

I can see how they could disappear for a few days.


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## dougolasjr (Mar 3, 2010)

I guess time will tell.


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## MABJ (Mar 30, 2012)

Hmm. The issue may be there are five in a 10 gal tank. I would bet three would be perfectly suited for a two gal, and five perfect for a three gal.


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## dougolasjr (Mar 3, 2010)

The tanks was pretty much empty. I guess I may have to get some more.


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## AVN (Oct 3, 2012)

The water level isn't high enough for them to climb, the heater looks like the only escape point. I doubt they left though, your tank looks like a perfect habitat.

They're mud crabs, so expect them to hide during the day and to come out at night.


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## dougolasjr (Mar 3, 2010)

Yea, I doubt they left. I would bet they just are hanging out in the moss even at night.


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## dougolasjr (Mar 3, 2010)

I actually just saw two tonight after the lights were out for awhile. One was in the feeding dish he scurried away when I turned on low light. Then later on I saw two hanging out in the moss.


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## dougolasjr (Mar 3, 2010)

I was able to catch one out in the open on the side of the tank that faces the wall. Had to squeeze in to try and get pictures. I swear my phone will focus in and it looks great then it continues to focus and it gets fuzzy.


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## AVN (Oct 3, 2012)

Hm, these guys might not be so cool in invert tanks if they just hide all the time!


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## Sake (Mar 30, 2012)

I'm sure they're just exploring the moss and will get bored soon enough and explore the open areas once the are comfortable.


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## dougolasjr (Mar 3, 2010)

Sake said:


> I'm sure they're just exploring the moss and will get bored soon enough and explore the open areas once the are comfortable.


Another one was just roaming around in the open so maybe they are just getting comfortable.


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## dougolasjr (Mar 3, 2010)

*Molt I Hope*

So I checked the tank this morning, and noticed a crab sitting in the moss. So when I turn on the light no movement. As I watch it doesn't move at all. I start to think it died. So I wait some more and nothing. I thought it looks kinda clear ish maybe its a molt. So I moved it to the substrate to get some close up pictures with the micro camera. Do you think its a molt?


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## MABJ (Mar 30, 2012)

I think it is a molt. Take a tweezer to it and try to test its integrity.


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## xiaxia (Mar 11, 2008)

+1 the molt. crab molts are crazy.


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## Sake (Mar 30, 2012)

looks like a molt to me, the eyes aren't a dark color, if it was a dead crab I think they eyes would be a give away.


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## dougolasjr (Mar 3, 2010)

MABJ said:


> I think it is a molt. Take a tweezer to it and try to test its integrity.



I will just hope its a molt.


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## AVN (Oct 3, 2012)

Definitely a molt. Crabs don't lose their coloration like shrimp when they die. I bred Mangrove and Vamp crabs and dead ones would retain coloration for weeks until they fully rotted and left their shell behind.

Molts are semi-translucent and crunch when you squeeze them. You can see through the legs, very distinguishable for molts.


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## dougolasjr (Mar 3, 2010)

Thanks for all the information. What would I do without this place.


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## dougolasjr (Mar 3, 2010)

So I found another molt. I was able to catch one of the crabs sitting on the outside of the moss. The best picture I could get before he went all the way back in is below.


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## Sake (Mar 30, 2012)

Yay molts are definitely a good sign they must be growing


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## dougolasjr (Mar 3, 2010)

I hope so. I think I caught one of the ones that molted out. I was able to snap some not so good pics. He/She is bigger than anything I received.


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## Sake (Mar 30, 2012)

Do they seem to be coming out in the open any more?


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## dougolasjr (Mar 3, 2010)

The one in the picture just sat as I took pictures. Normally they had been moving pretty quickly into the moss once the light came on and I tried to take pictures.


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## dougolasjr (Mar 3, 2010)

Just won another auction from the same guy for 3 more.


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## Sake (Mar 30, 2012)

Nice, going to have a nice colony then  They seem to be eating well? I wonder how many you could keep together.


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## AlanLe (Jan 10, 2013)

Are crabs in general safe with plants?


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## MABJ (Mar 30, 2012)

There really isn't an in general. There are too many varieties to make an umbrella statement. 

I don't know about these -- they seem it -- but the Thai Micro Crabs are.


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## dougolasjr (Mar 3, 2010)

I really haven't seem them munching on any plants. They could be eating some of the moss tho. I haven't really seem them eat much of anything. I suppose they mostly come out at night. This morning I was able to catch 3 sitting on the moss in different areas. They didn't scuttle away when I turned the lights on so maybe they are getting used to it. I would have got some pictures but I noticed a blue Malawa in my other tank and well I got distracted with taking bad pictures of them.


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## dougolasjr (Mar 3, 2010)

More Pictures. Taken with Micro USB camera


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## CookieM (Feb 7, 2012)

I wonder how much you buy these for? Because back in my country we eat these by the thousand. And it cost less than $2 to burst your stomach.


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## dougolasjr (Mar 3, 2010)

They are less than a inch in size. I doubt anyone would eat them.


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## Soothing Shrimp (Nov 9, 2011)

By the handfull. Like peanuts.


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## dougolasjr (Mar 3, 2010)

Yea maybe that.


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## Sake (Mar 30, 2012)

I really like that first pic, they just look soo darn cool.


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## dougolasjr (Mar 3, 2010)

They seem to be getting used to the tank. I've seen them out and about all day. They look funny scuttling sideways.


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## Sake (Mar 30, 2012)

dougolasjr said:


> They seem to be getting used to the tank. I've seen them out and about all day. They look funny scuttling sideways.


Then what's your excuse for not posting more pics! hahaha Glad they are doing well for ya. Seen any more molts yet?


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## dougolasjr (Mar 3, 2010)

I have more pictures just haven't got around to uploading and posting. No more molts I was able to measure a few. They like to back up against the glass. So far none of the ones I have been able to measure is over and inch from leg to leg the.


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## MABJ (Mar 30, 2012)

Awesome pics  

Seen any fighting/congregating between the crabs?


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## dougolasjr (Mar 3, 2010)

I have not seen any fighting. I was able to catch 3 out and about. I feed them using a glass dish, and they have no problem climbing in and taking food away with them or just eating there. There are 3 crabs in pictures 2-3.


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## Sake (Mar 30, 2012)

See just needed a bit of time to come out! So glad they are doing well for ya they seem like cool critters.


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## dougolasjr (Mar 3, 2010)

Yea they are cool little guys. I have some more coming in today.


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## dougolasjr (Mar 3, 2010)

Crabs arrived safely. He also sent extras. I have 6-7 more.


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## Sake (Mar 30, 2012)

Nice how many total is that now? Hopefully you can breed them. Wonder if they'd have to be bred in salt water though, I know they are in freshwater I just can't remember if they can breed in freshwater.


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## dougolasjr (Mar 3, 2010)

I guess we will see. Even if they can breed in fw who knows what the young would require.


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## MABJ (Mar 30, 2012)

Nice!! I'll be watching carefully to see if I could add some to my community tanks. 

And by community, I mean invert safe.


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## dougolasjr (Mar 3, 2010)

Bad news when I got home I realized that I only had 3 alive crabs. Their were 4 that had died along the way.


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## MABJ (Mar 30, 2012)

:x that's awful. Do you know why they died? Just shipping hardships?


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## dougolasjr (Mar 3, 2010)

Not sure. I only took a cursory look at them when they arrived. I was at work at the time. So I am not sure exactly. I would have had them shipped later if I would have remembered about Monday being a holiday.


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## dougolasjr (Mar 3, 2010)

*Mud Crabs*

Pics. Hanging out in the Moss. They like to take food and run away with it. I put in some of the heavier food that even my ghost shrimp can't lug away and lo and behold it was not in the feeding dish 5 mins later.


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## wicca27 (May 3, 2009)

sorry you lost some, was it the new ones or some of the ones you have had a while?


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## MABJ (Mar 30, 2012)

I'm breaking down >_> I think I may need a few of these. Just trying to figure out if they'll be ok with Least Killifish and shrimp. Hmm


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## Kehy (Feb 5, 2012)

MABJ said:


> I'm breaking down >_> I think I may need a few of these. Just trying to figure out if they'll be ok with Least Killifish and shrimp. Hmm


I'm trying to figure this out too. I have...least killifish and shrimp. hahaha


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## sugarbyte (Apr 3, 2011)

They're so cute :3


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## MABJ (Mar 30, 2012)

Kehy said:


> I'm trying to figure this out too. I have...least killifish and shrimp. hahaha


Quick side bar -- my killis don't go after my shrimp or shrimplets.. Is that also true for you?


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## dougolasjr (Mar 3, 2010)

*Mud Crab Hole*



wicca27 said:


> sorry you lost some, was it the new ones or some of the ones you have had a while?


It was the new ones. As I was getting them ready to put into the tank I realized they had died. 


Side note they do seem to like to dig. One of the crabs made a little cave hole underneath a clay tray. He/She is also the one that took the big piece of food all for himself.


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## dougolasjr (Mar 3, 2010)

MABJ said:


> I'm breaking down >_> I think I may need a few of these. Just trying to figure out if they'll be ok with Least Killifish and shrimp. Hmm


I might eventually put some shrimp with them after I have had them for awhile. The other option I want to try is doing a sand substrate tank, and seeing how they like that. I read that the females partial bury themselves when egging up. Right now they are in Eco Complete substrate so not sure how well that would work.


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## MABJ (Mar 30, 2012)

Well neat. If you decide to keep some cherries in, let me know.


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## dougolasjr (Mar 3, 2010)

*Malawas*



MABJ said:


> Well neat. If you decide to keep some cherries in, let me know.


I would probably go with adding some Malawas' actually they seem to be even more hardy/tough then cherries.


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## MABJ (Mar 30, 2012)

Nice. They're a pretty shrimp.


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## dougolasjr (Mar 3, 2010)

Yea they throw out all kinds of colors. Most I have are dark or light colored. Caught one that was blue the other day.


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## MABJ (Mar 30, 2012)

So pretty! Do they change colors depending on certain factors?


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## dougolasjr (Mar 3, 2010)

To be honest I do not know. They may change depending on the food.


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## Kehy (Feb 5, 2012)

MABJ said:


> Quick side bar -- my killis don't go after my shrimp or shrimplets.. Is that also true for you?


Mine go after newborns...but they also go after their reflections. I have more issues with the shrimp bullying the fish!


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## dougolasjr (Mar 3, 2010)

I do believe they also eat plant matter. I saw what looked like one munching on either some dead java moss or live java moss couldn't tell that well, but it could have been something else.


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## dougolasjr (Mar 3, 2010)

Just some more pictures.


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## wicca27 (May 3, 2009)

MABJ said:


> Quick side bar -- my killis don't go after my shrimp or shrimplets.. Is that also true for you?


mine dont go after shrimp i have them with crs but there is a fair bit of moss in there too.

i love the blue shrimp, my greens get crazy colors like that from time to time. not sure what they really are though. the crabs are cool but so not a fan of pinchers of any kind in my tanks lol


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## dougolasjr (Mar 3, 2010)

Are they Green Neos? The crabs pincers don't seem all that strong, but I really haven't seem them use other than grabbing food and walking away with it.


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## MABJ (Mar 30, 2012)

*Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

I'm not sure if there is a way to test pincer strength lol. 

I wish there was so you could give a definitive answer. 

I know my CPOs have fairly strong pincers. I've seen them do neat things with them. Including grab my planting tongs to show them who's boss.


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## dougolasjr (Mar 3, 2010)

More Pics.




















Made himself a nice little home..


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## MABJ (Mar 30, 2012)

*Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Very nice! That means they burrow then?


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## dougolasjr (Mar 3, 2010)

It looks that way. They probably have burrowed under all the ss mesh and ceramic tiles.


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

One of the three I bought today. Don't know the species.


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## dougolasjr (Mar 3, 2010)

Hmm kinda hard to tell, in this picture they look closer to the same type. The other picture it looked different.


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

In the fish store (in Seattle, btw), I think the clearest one in the photo was standing. In the bowl they're huddled down trying to hide. 

In the stance he held at the shop he looked very similar to our spider crabs, only tiny. 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Your crabs look more like the kinds we find on our beaches with a flat face, while the ones I have have a rather pointy face. 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

A pic from the Net... A thai micro crab with a Tiger shrimp. Looks a lot like mine.


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Just a couple more and I'll shut up! 
In the tank:


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

They have long hairs on their "arms", thinking some filter feeding goes on.


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## dougolasjr (Mar 3, 2010)

Based on that pics. Yours look more like Thai micro crabs. Longer legs and more curved pincers.


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## MABJ (Mar 30, 2012)

*Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

They definitely are. Those are guaranteed shrimp safe. Their bodies should be little more than the diameter of a pencil eraser


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## dougolasjr (Mar 3, 2010)

I didn't realize that Thai crabs were that small. The body of the mud crabs is around 2-3 pencil erasers.


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## MABJ (Mar 30, 2012)

*Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Yeah. So if Rob's crabs aren't 1-2 pencil erasers small, they may not be Thais. But I've read so much on them, and while their coloration can fluctuate, they look very much like that.


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## dougolasjr (Mar 3, 2010)

I amend that statement they look like more 1-2 in body, but the legs look thicker than thai crabs. Also the thai crabs have more curved pincer arms whereas the mud crabs are more of the more regular crab shaped pincer arms .


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## MABJ (Mar 30, 2012)

*Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Ahhhh yeah. The body is how I often read their size measured.


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## dougolasjr (Mar 3, 2010)

I think the biggest difference is size and how the pincers are positioned. The thai micro crabs seem to have smaller pincers and hold them folded underneath the body. With the mud crabs they seem to have bigger pincers and hold them out in front.


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## dougolasjr (Mar 3, 2010)

I have been noticing empty shell snails, but I attributed it to being there before I put the crabs. So yesterday I put some more Rams snails of different sizes into the tank. I just noticed that there is a snail shell that looks broken with a dead snail partial in it. It could be that I smashed a snail on accident when transferring them. I guess I will need to see if more empty shells show up.


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Here's an update (Hope you don't mind!) These guys are very hairy this one on his side keeping at least one "toe" out of the water. I put a small amount of spirulina in the tank, thinking he's catching it. 

Turns out there is one male and two females.


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

They are definitely smaller than two erasers across. Much closer to one.  

Sent from my Samsung Galaxy S III using Tapatalk 2


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## mr2 (Jul 31, 2010)

Those are so cool!


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## dougolasjr (Mar 3, 2010)

Yea those are Thai micros. They were what I was originally going to get for the tank until someone else started the thread about the mud crabs. According to some of the articles, on mud crabs, they can and do have a full life cycle in fw bodies of water. Hopefully it can be repeated in the aquarium setting. If i remember correctly Thais also can do a full life cycle in fw but no one has been able to repeat the process in the aquarium.


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## MABJ (Mar 30, 2012)

*Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Thais do have a full cycle in fresh. We just haven't figured out how. 

They are Thai, Rob. They feed by catching particles in their hairs and eating them. 

I started the thread on mud crabs because I'd never seen them before anywhere, let alone on eBay.


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

I do like your mud crabs, they're very cute! 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## dougolasjr (Mar 3, 2010)

One of my crabs is bigger than the rest. Not sure if it is a female and the others are male because it looks bigger. I wasn't able to get pictures of it to show size reference. All the pics I have so far are of the smaller crabs. 

More pics.


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## Rob in Puyallup (Jul 2, 2009)

*Re: Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Doug... Crabs are easy to sex. If you can see their undersides. Males have a much narrower "apron" than females. 

The apron is like a tail folded under their bodies, is where the female carries the eggs. 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## dougolasjr (Mar 3, 2010)

Yea seeing the underside is the problem. Next time I have some blue crabs in for supper I will defiantly check that out. I did notice a molt this morning turned upside down let me check out the picture.


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## dougolasjr (Mar 3, 2010)

Well I went ahead an ordered some more to replace the ones that passed. They arrived today the order was for 4 he sent 6, and one looked to have egg sac. They were all alive so I put everything back as I received it till I can get home and get them in the tank.


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## MABJ (Mar 30, 2012)

*Mud Crabs Have Arrived --- Rhithropanopeus harrisii*

Very nice. How many will that be in this tank?


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## dougolasjr (Mar 3, 2010)

I'm not sure to be honest. I didn't really keep up with it.


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## dougolasjr (Mar 3, 2010)

Female with what I assume are eggs.



















More


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## dougolasjr (Mar 3, 2010)

*Eggs*

Came home to the crabs out and about. The one with eggs was right next to the glass. So I got some more pictures of the crab with eggs. Able to get pretty close up with micrco usb camera.


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## KenP (Nov 8, 2012)

Wow. There must be hundreds of eggs. Nice detail of eggs in third picture.


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## dougolasjr (Mar 3, 2010)

Yea I used a light to get a better picture.


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## MABJ (Mar 30, 2012)

Wowwwww nice. That's really neat looking. I REALLY hope you get babies. 

When they hatch, do you have anything to feed them?


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## dougolasjr (Mar 3, 2010)

I was going to try my shrimplet food from Jake aka somewhatshocked.


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## abc (May 18, 2004)

great photo! thanks for the egg pics for the mud crabs. this is the first time I've seen a pregnant crab. very neat!


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## MABJ (Mar 30, 2012)

dougolasjr said:


> I was going to try my shrimplet food from Jake aka somewhatshocked.


I love Jakes foods. Haven't tried his baby food yet tho! I haven't had babies to try it out on. I have some waiting though.


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## dougolasjr (Mar 3, 2010)

Yea luckily she was backed up against the glass which is the perfect spot for the micro usb camera.


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## KenP (Nov 8, 2012)

You can try shrimplet food but they eggs hatch into larvae. I believe they will need something else. Live food.


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## HX67 (Jul 15, 2010)

KenP said:


> You can try shrimplet food but they eggs hatch into larvae. I believe they will need something else. Live food.


I agree.
Most crab babies typically hatching in brackish/salt fare well on artemia when they hatch. Larvae is free-swimming and prefers pelagic live food.

If these guys do it like, say brackish _Sesarma_s, then the female lets the eggs go free with the waterflow prior to hatching.

Are you going to give the eggs/larvae any salt, or keep them in fresh?

Great going! Thanks for updating.
Interesting to see how they do for you.


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## dougolasjr (Mar 3, 2010)

MABJ said:


> I love Jakes foods. Haven't tried his baby food yet tho! I haven't had babies to try it out on. I have some waiting though.



Yea, I pretty much use all his foods and supplements.


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## dougolasjr (Mar 3, 2010)

I plan on keeping them in freshwater. They have living colonies in fresh and brackish waters so I figured they might be okay. Not sure what live food I could raise or buy. Do you think freeze dried brine shrimp would work.


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## HX67 (Jul 15, 2010)

I read


dougolasjr said:


> I plan on keeping them in freshwater. They have living colonies in fresh and brackish waters so I figured they might be okay. Not sure what live food I could raise or buy. Do you think freeze dried brine shrimp would work.


All freezedried brine shrimp I've ever bought has been "adult" brine shrimp, so can't give an answer here.
The reports I've read on breeding crabs have involved newly hatched brine shrimp (_Artemia salina_) as a basic diet for the larvae.
Making _Artemia_ hatchlings happen is really easy, eggs are offered in almost every LFS. No sweat!

Reports furthermore state that growing the crab larvae (brackish species) in brackish is not only more efficient, but also easier, because brine shrimp eggs actually hatch at the same levels of salinity that the crab larvae is comfy in...

I spent an hour trying to find an article I read on the subject, but it seems to have vanished from cyberspace.
This one might be of some use:
http://www.aquaticcommunity.com/inv/redclawmangrovecrabs.php
Different species, I know, but I have a feeling there might be similarities to take advantage of?

Good luck!


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## dougolasjr (Mar 3, 2010)

I may go with instant baby brine shrimp stuff from amazon. I don't think I have the patience time or space to try raising them. 

http://www.amazon.com/s/ref=nb_sb_noss_1/175-0494904-8388649?url=search-alias%3Daps&field-keywords=brine+shrimp


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## HX67 (Jul 15, 2010)

Wow, that stuff seems perfect.

Might be a bit trickier to feed than live. I'd imagine that dead brine shrimp nauplii sinks to the bottom of the tank (while crab larvae is pelagic) and there could be a risk of overfeeding?
But with some sort of water circulation, perhaps a smallish rearing tank with air stone, it could be made to work?

In the article on rearing crab babies I mentioned earlier, they used a rearing tank with quite a small footprint and an airstone, to keep everything moving and not collecting to the bottom. They did use live brine shrimp, though.
Daily water changes, clean water. Brackish, at 1,006 or so, for _Sesarmas_.

Since these are mainly found in salty waters, I would seriously consider adding a bit of salt for the eggs/babies...
On the other hand, these crabs seem to be extremely prolific and you'll probably get more chances to try it out later.

Keep us posted.


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## dougolasjr (Mar 3, 2010)

Daily water changes and all that are more than I would be able to do. During the week keeping up with 6 other tanks and normally being gone 11-14 hours I would probably not keep up the schedule. I read on the brine shrimp stuff from amazon it stays floating in the water column for a good amount of time. I will def keep you posted.


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## KenP (Nov 8, 2012)

Doug check this out about larvae development:

adults occur in salinities from about 0–18 ppt (Ryan, 1956) in estuaries; Rhithropanopeus harrisii can be found in estuaries and quasi-freshwater lakes with salinities as low as 0.4 ppt (Keith, 2006)

The mud crab, Rhithropanopeus harrisii has been found in 10 freshwater impoundments in Texas. Breeding populations were confirmed in eight of these reservoirs by the presence of gravid females, juvenile crabs, and zoeae in the plankton. Salinities varied from a low of 0.5 at Tradinghouse Creek Reservoir to a high of 3.0 at Lake Colorado City. A salinity of 0.5 is considerably below that reported previously for larval survival. Crabs were induced to breed in the lab at a salinity of 1.9 and hatching occurred at salinities as low as 0.5 (Terrence Boyle, Jr., Donald Keith & Russell Pfau, 2010)

Accordingly, studies show that they can develop to the first crab stage in salinities from 2.5 to 40 ppt and temperatures of 15–35 °C (Costlow et al., 1966; Costlow and Bookhout, 1971; Christensen and Costlow, 1975; Rosenberg and Costlow, 1979; Morgan, 1987a; Laughlin, 1989; Laughlin and French, 1989a, b)


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## KenP (Nov 8, 2012)

Doug I believe the salinity units in paragraph two are ppt. It would seem that you could try very low salinity but not zero salinity. Would 0.5 ppt harm your plants and other critters?


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## dougolasjr (Mar 3, 2010)

I don't know the only other critters in there are rams snails. I might try it tho I will see what happens for a month or two.


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## dougolasjr (Mar 3, 2010)

I do have a new 5g I may convert to brackish once some hitch hickers get big enough to catch.


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## HX67 (Jul 15, 2010)

I'd suggest putting up the 5g, catching the female with the eggs into it, slowly adding some salt and waiting for it to loose the eggs...

Great info, KenP!


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## dougolasjr (Mar 3, 2010)

I think I will just wait and see what happens. I already have the 5 up.


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## dougolasjr (Mar 3, 2010)

Only bad updates. I have had 3 crabs die this past week. The one with eggs was the last one to die. Not sure why.


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## MABJ (Mar 30, 2012)

Really :/ that's very unfortunate. I'm sorry to hear that.


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## Rob in Puyallup (Jul 2, 2009)

Sorry about the news, Doug. 

I haven't seen my crabs since they went into hiding. 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## dougolasjr (Mar 3, 2010)

Yea they do seem to hide alot. I believe all the ones that died were from the newer batch.


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## KenP (Nov 8, 2012)

Sorry to hear about the crab losses. I plan starting a tank in spring but brackish with Opae.


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## dougolasjr (Mar 3, 2010)

Yea I have a 5G I am going to do brackish.


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## dougolasjr (Mar 3, 2010)

More Crab pics on a rainy day.


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## dougolasjr (Mar 3, 2010)

Well no deaths lately. I think all the deaths were the third batch. In one pic you can see one crab munching on Jake aks somewhatshocked's veggie sticks with calcium. So They like that and small snails.


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## KenP (Nov 8, 2012)

Glad to here the deaths have stopped. I like the third image with the snail. Again my offer to provide some Opae stands if you are planning a mixed tank.


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## dougolasjr (Mar 3, 2010)

The nerite snail I just through in there. If you look to the left there is snail shell that's missing parts. There are quite a few shails like that. I doubt I do a mix tank. I am going to do a opae tank.


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## dougolasjr (Mar 3, 2010)

Not sure what is going on in the pictures below.... 

Two crabs.

To me it looks like... baby making... One just scurried of while posting this..


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## dougolasjr (Mar 3, 2010)

And now one is eating a snail.... breaking the shell and all.


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## Kehy (Feb 5, 2012)

This might have been answered already, but do they go after shrimplets or fish fry? I've been having a lot of issues with micro ramshorns snail, and if these guys will eat those, I may be taking a closer look at them


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## AquaPipes (Jun 4, 2012)

My hunch would be they'd eat baby shrimp, or even adult shrimp if they manage to catch one.


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## dougolasjr (Mar 3, 2010)

I would think they would eat most anything they can catch. I would assume you could keep them with shrimp that breed readily. If you give them plant matter and snails to eat, both of which are much slower than shrimp.


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## Rob in Puyallup (Jul 2, 2009)

Look who came out of hiding this afternoon. Still another one in the tank somewhere...


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## dougolasjr (Mar 3, 2010)

Cool pics. I guess they hide more than the mud crabs do. I can almost always see one or two of them out hanging around.


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## GreenBliss (Mar 7, 2012)

Any updates?


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## Indychus (Feb 21, 2013)

Just found this thread! I have harris mud crabs in my 20H community tank. Started with 5, but lost 3 within the first two days. The other 2 have been fine for around a year now. They hide a lot and don't bother the fish, but they are ruthless towards the ramshorn snails in my tank... they just pull them apart then eat whatever isn't crunchy. The will climb up onto the heater, but have never tried to escape or seemed like they wanted to get out of the water.


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## dougolasjr (Mar 3, 2010)

GreenBliss said:


> Any updates?


NO new updates. They live they eat and destroy ramshorns snails. I actually have pictures of them eating one. Its pretty something. I haven't got around to posting them.


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## dougolasjr (Mar 3, 2010)

*Snail Murder.*

Caught in the Act.


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## MABJ (Mar 30, 2012)

Hungry fellas


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## dougolasjr (Mar 3, 2010)

MABJ said:


> Hungry fellas



Yea. You should see the number of empty shells on the ground. They have not gone after the one Malawa shrimp that is in there.


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## MABJ (Mar 30, 2012)

I didn't figure they'd go after shrimp at all. I would love to try a few of these guys.


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## FisheriesOmen (Jan 14, 2012)

Definitely sub'ing to this. I would love to get some of these for my 10g. If it wasn't for my FW riparium plants I would be all over turning mine into a lightly brackish tank!


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## dougolasjr (Mar 3, 2010)

They are in freshwater.


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## FisheriesOmen (Jan 14, 2012)

dougolasjr said:


> They are in freshwater.


I've read through your entire thread but I feel like it would be more fun to do a slightly brackish tank. If it wasn't for my riparium plants that I got I would be all for trashing my aquatic plants that aren't as tolerant and just getting some hardier brackish plants.


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## AquaPipes (Jun 4, 2012)

How about MTS, will they eat the small ones? If so, I'm buying some of these guys.


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## dougolasjr (Mar 3, 2010)

I haven't seen them go after MTS. I will double check when I get home. They mostly eat the Rams since they are easy to get to.


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## Open_Cages (Jan 26, 2013)

Have you reared any in fresh water? I read the entire thread but only saw the pictures of them mating.


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## Acro (Jul 7, 2012)

Any news on these amazing crabs?


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## dougolasjr (Mar 3, 2010)

Unfortunately they all perished and I had to tear down the tank for a baby room.


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## MABJ (Mar 30, 2012)

quite the sad news.


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