Mud Crabs Have Arrived ,Rropanopeus harrisii, Now with Eggs

[dougolasjr]

Originally Posted by MABJ

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.

[dougolasjr]

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.

[HX67]

I read

Originally Posted by dougolasjr

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/...grovecrabs.php
Different species, I know, but I have a feeling there might be similarities to take advantage of?

Good luck!

[dougolasjr]

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_no...s=brine+shrimp

[HX67]

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.

[dougolasjr]

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.

[KenP]

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)

[KenP]

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?

[dougolasjr]

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.

[dougolasjr]

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

[HX67]

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!

[dougolasjr]

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

[dougolasjr]

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.

[MABJ]

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

[Rob in Puyallup]

Sorry about the news, Doug.

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

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