Attempting to Breed Microcrabs - Page 3 - The Planted Tank Forum
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post #31 of 78 (permalink) Old 02-28-2012, 09:09 PM
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Originally Posted by lipadj46 View Post
they are shrimp safe. I have 10 coming tomorrow to add to my shrimp tank.
really..


very interesting..
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post #32 of 78 (permalink) Old 02-28-2012, 10:38 PM
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Has anyone heard of/tried keeping them with CPOs? I would like to add some to my tank but Not sure. I tried a baby Marm But "it" immediately started seeking out the Crabs so I removed him before anything can happen.
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post #33 of 78 (permalink) Old 02-29-2012, 12:33 AM Thread Starter
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Still being thwarted by the female crabs. I've got 7 in a hatching tank, waiting for them to release their zoeas. There are two or three berried females in the main tank as well, but I have not seen any activity out of them either. Two of the crabs have been holding their eggs for at least 3 weeks in the holding tank; they've got to be about ready to burst.

I rearranged things somewhat, floating my hatching tank in my main crab tank (a 20L). It will keep the crabs' temperatures up about 5-8F compared to ambient room temperature and might give me a bit more luck with the zoeas. This has been the case for a week or so now. The hatching tank also is getting much more light at this point and algae is growing on the walls. There are places for the crabs to hide though, and they seem OK with the confinement.
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post #34 of 78 (permalink) Old 02-29-2012, 03:05 PM
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I read there is a stage where the Zoeas bury themselves in the sediment where they
begin eating organisms in a manner similar to the adults to begin the next stage. Not sure if this is true for this species of crab. But from reading all accounts on breeding micro-crabs and keeping the Zoeas alive, none have tried putting a patch of dirt/fine grain sand in their tanks. Maybe this would be worth a try.
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post #35 of 78 (permalink) Old 02-29-2012, 03:35 PM Thread Starter
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Thanks for the suggestion. At this point I'm just trying to get zoeas still.
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post #36 of 78 (permalink) Old 02-29-2012, 03:57 PM Thread Starter
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This morning I found one of my berried crabs dead, or very nearly so. I removed all of the remaining females to the main tank and tried putting the immobilized crab in a container of clean tank water, but no luck. I don't know why she died, the water tested clean and the other inhabitants were perfectly fine.

While it was disappointing to lose a crab, particularly a berried female, this gave me an opportunity to try hatching the eggs artificially. I broke out my dissecting microscope and went to work, and I took a few pictures along the way. My camera is nothing special at all, and the pictures were taken by holding it up to an eyepiece, so these are not works of art, but they are instructive. The view through the eyepieces is much better, both wider and clearer.

A dorsal shot of the crab.
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These crabs are described as setose or pilose, because they have a number of hairy protrusions called setae. This species in particular is very pilose, thus its genus name Limno (lake) pilos (hairy.) This is a shot of one of the chelipeds. This individual is not particularly setose compared to some that I have, but the setae are very easily seen.

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A ventral shot of the crab. The entire yellow portion of the body is actually the tail, curled under the crab's abdomen. Immediately above the tail are two small openings called the gonopores (which I really wish I had gotten a picture of) through which the eggs are deposited on the tail.
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Because the animal had been dead for a time, its body was relatively stiff. I tried to get an image of the tail while it was still attached to the body, but couldn't manage to get the camera and tweezers to cooperate. I removed the tail.

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In spite of its appearance as being completely laden with eggs, none of the eggs are actually attached to the tail. Instead of depositing its eggs on normal pleopods, this species appears to attach them to special, feathery protrusions (more setae? very oddly adapted and attached pleopods??) from the edges of the tail. The eggs are attached to the protrusions in groups of 20, with perhaps 10 or so of the protrusions present. Here is an image of one of these feathery protrusions, with eggs and the tail present for comparison. Any eggs not attached directly to the feathery protrusions were directly attached to other eggs.

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After removing the eggs, I placed them in a container of tank water and installed an air stone. The eggs are too small to hatch by tumbling, so I intend to keep the water in the tank well aerated and circulating, and to stir the eggs several times daily. The vast majority of the eggs are detached from everything, but 10-20% are in small clumps still. I've got my fingers crossed, both for the eggs and the remaining females that are back in the tank.
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post #37 of 78 (permalink) Old 02-29-2012, 03:58 PM
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Sorry to here about the lost,

Good luck.
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post #38 of 78 (permalink) Old 03-06-2012, 06:27 PM
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Hi there, I've read somewhere that the zoeas are carnivorous from the very start.
I have just moved my first berried female to her own tank that I have been breeding
all kinds of micro-beasties in, also got at least 5 types of phytoplankton. She mated 5 minutes after I introduced her into my regular shrimp tank. The shop didn't put any foliage in with them (6) and when I got home they were all tangled together
in a ball, didn't seem bothered though, they all dispersed peacefully enough once released.
Anyone know how long it takes from mating to egg release?
They mated exactly a month ago today.
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post #39 of 78 (permalink) Old 03-06-2012, 09:20 PM
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This morning I found one of my berried crabs dead, or very nearly so. I removed all of the remaining females to the main tank and tried putting the immobilized crab in a container of clean tank water, but no luck. I don't know why she died, the water tested clean and the other inhabitants were perfectly fine.

While it was disappointing to lose a crab, particularly a berried female, this gave me an opportunity to try hatching the eggs artificially. I broke out my dissecting microscope and went to work, and I took a few pictures along the way. My camera is nothing special at all, and the pictures were taken by holding it up to an eyepiece, so these are not works of art, but they are instructive. The view through the eyepieces is much better, both wider and clearer.
Thanks for sharing, Your Pics are some of the best that I've seen out here, Keep them coming.

What temp do you have your Hatchery at? And How many eggs total would you guestimate?
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post #40 of 78 (permalink) Old 03-07-2012, 01:03 AM Thread Starter
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Thanks for sharing, Your Pics are some of the best that I've seen out here, Keep them coming.

What temp do you have your Hatchery at? And How many eggs total would you guestimate?
The eggs are in a Dip N Pour (roughly 1 quart container) floating in my main shrimp tank. It's at 73 F. There were 100-200 eggs on the crab. They are larger eggs than amano shrimp have, so I'm expecting larger, more developed zoeas from them. That's the general trend with crustaceans, in any case.
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post #41 of 78 (permalink) Old 03-07-2012, 01:44 AM
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fascinating!! I am so glad you are documenting this. I hope you continue to take pictures of your efforts.
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post #42 of 78 (permalink) Old 03-25-2012, 06:52 PM Thread Starter
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The eggs that I was trying to hatch artificially were all devoured by some sort of pest worm about two weeks ago. There was much swearing in the Patterson household the morning I found them out. In happier news, I finally have zoeas in my main tank. I've collected about 20 of them with a pipette and transferred them to a holding tank until I decide what I'm going to do with them exactly.

The first thing I attempted was to see whether they required brackish conditions to develop. I removed 5 of them and transferred them to my amano zoea growth tank. It would appear that they do not need brackish conditions, as all 5 were dead within an hour. That said, it is possible they require a lower salinity than is present in that tank (1.017 at the moment) or an easier transition to brackish water (which would be completely unlike the other species I've been working with that require brackish.)

The remaining zoeas are currently in the Dip N' Pour floating in the main tank, waiting for me to collect more of their brothers and sisters. I've added a tiny amount of 5-50 micron golden pearls as food, as well as some pond/green water that I've been culturing. Hopefully they find something in the mix that they want to eat.

I took some pictures of one of the zoeas with my dissecting scope. It was alive at the time, and the lighting wasn't great, but there was a lot to see and some of the zoeas behaviors are more clear now, particularly their movement patterns. It was also nice to be able to confirm that this was indeed a crab zoea and not some other sort of zooplankton. I'll post some of the images later today or perhaps tomorrow, along with an update about the routine I'm following.

ETA: Sick kid today, so my day off while she was at preschool became the let's pretend this is the Patterson General Medicine Center day. Hopefully I'll be able to get the pictures going Tuesday, or Wednesday at the latest. I plan on taking pictures each day until the zoeas develop or die (or I see something shiny and lose track.) It does appear that they are eating though, both in the main tank and in my growout container.

Last edited by jasonpatterson; 03-27-2012 at 02:13 AM.
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post #43 of 78 (permalink) Old 03-28-2012, 07:44 PM Thread Starter
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Once I had a chance to review the images I've taken of the zoeas, I found them to be pretty poor, to put it delicately. I'm posting what I've got, because even these terrible pictures have something to show, but hopefully I can improve their quality tomorrow and beyond. Some of the observations I'm making here are not readily visible in the images. The quality of the image through the microscope is vastly better than what I've been able to capture thus far. I'm working on improving the image quality, but I also can't afford to spend money on better cameras, optics, and lighting, so I wouldn't get my hopes up if I were you.

Day 1 (Or possibly later, this is when I saw them in the tank. I suspect it was the morning after they had hatched though.) -

The zoea has eyes that are still a part of its body, almost eyespots, rather than being at the end of stalks. When they swim, they move very slowly, but will occasionally jerk rapidly in the water. The jerking motion occurs when they extend their tail (curling upward on the right side of the zoea shown below), which is normally tucked into their exoskeleton. It didn't appear clearly in this picture, but the zoeas have spikes both on top of their heads and on their sides, which is a characteristic of crab zoeas in general. The animal is essentially spherical at this point, about 0.1mm in diameter.

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Day 2 -

The zoea looks much the same in this picture, though it does show signs of change. The coloration is much darker overall and the beginnings of appendages growing from the head are visible. The tail is tucked under the animal's exoskeleton in this image, curling upward on the left side.

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Day 3 - No image. I hope to be able to return and complete the set of development photos at a later date.

Day 4 -

Major changes are taking place in the zoea's development. The eyes are now external to the body, at the end of stalks. The gills are also much larger and more active. It's possible to see one of the side spines at the bottom right of the animal as well.

This image is a dorsal view of the animal, rather than the lateral views that came before. I was able to view the earlier zoeas in the same position but did not manage to get any pictures of them while they were turned this way. On earlier days there was almost nothing additional that was visible at this angle. The gills were small and barely visible and the clearish area on the bottom left of the animal in this picture (where I have indicated gills) appeared to be completely empty.

I apologize for the quality of this image, but believe me, it was far and away the best I took. I really need to improve my lighting for my dissecting scope so that I can compensate for faster moving specimens. I also had my first zoea death, and I'm afraid that it might have been one of the specimens I examined earlier, so I'm trying to be more gentle with them from here on.

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post #44 of 78 (permalink) Old 03-28-2012, 07:53 PM Thread Starter
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General notes on the care I've given them so far -
The zoeas I have captured are living in a 1/2 gallon container that is floating in a larger aquarium. The temperature is 73 F, lighting is 12 on/12 off. In their container I have placed red root floaters, both because there are reports that the microcrabs develop in the roots of floating plants (water hyacinths are usually mentioned, even though they are not native to the area where microcrabs are from) and to try to help keep ammonia/nitrites/nitrates low. They have been fed a very small amount of 5-50 micron golden pearls, a smaller amount of spirulina, and a large quantity of cultured pond water. The cultured pond water contains a wide range of zooplankton and phytoplankton species. I've been doing small water changes daily. Only 1 zoea has died as of day 4, and I suspect that that may have been due to 'rough' handling in moving it to and from the microscope.

Behavior -
The zoeas have no interest in the floating plants whatsoever. They spend virtually all of their time at the bottom of the container, moving about slowly. They neither congregate nor avoid one another. They are not attracted to the lights at the top of the tank in any way either. When my next batch of zoeas hatch, I may test whether they burrow, as Smokeygrey suggests. At the moment they appear to be a flock of tiny, grey sheep, aimlessly grazing in a field.
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post #45 of 78 (permalink) Old 03-28-2012, 08:16 PM
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enjoying the updates. I found a TEENy crab in my tank today, about 1/3 the diameter of the smallest I have imported. i am thinking they were born in teh tank, but as I have not been paying close enough attention, there is no way to know for sure.
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