Breeding of the batik crab--Metasesarma obesum

[lucasjiang]

Well Lucas, at least you can be proud to be one of the few to breed them till this stage

That's quite an acheivement for someone your age

thanks for the encouragement desmond, will try my best

With the high motality rate the ammonia level will go up. Maintain good water quality... Usually fish farms when rearing lavae stage they don't change water (don't knw for how long) but due to your high motality rate you may have to change water but it's very risky cos at this stage of their development, they are very very fragal. Btw maybe next time you put in a very much bigger tank so that there is a bigger vol of water which makes the water more "stable".

hmm, i try to remove all the carcasses to prevent ammonia buildup.

Lucas, a very good job

thanks for the compliment, as said, will try my best

Rearing of crab larvae is tedious and will really test your patience and dedication. This is what I used to do. Get several transparent fishing tackle boxes like this (http://campingnfishing.com/index.php..._image&pID=306) and put three to four larvae into each compartment. Ensure you have plenty of clean and aged seawater to make one or two water changes to each compartment.

Food is the difficult part. If you have a laboratory dedicated to rearing larvae, there will usually be algae culture to feed the larvae. If not, you will have to hatch brine shrimp nauplii everyday until the larvae is large enough to take bigger day-old or bigger nauplii.

You will need to feed the larvae perhaps two to three times a day. Squirt enough nauplii for the larvae in each compartment (about 10 per larvae) and remove all uneaten nauplii after an hour. You can also make a water change at the same time when removing the nauplii.

Keep all the rearing boxes in a cool place. Some light source will be good but not so strong as to cook them. It is not really essential. After a few days, the larvae will start moulting. You will need to remove the moult. At the same time, you will have to thin out the larvae because the bigger ones will eat the smaller ones in the same compartment. In the end, you might have only one larvae in each compartment.

After enough moults, the larvae will finally reach a stage called the megalopa (big eyes) stage. This is the final larval stage and after one more moult, the crab will become a full-fledged juvenile crab.

This method is tedious and time consuming. Successful rate is possible 50% or lower. The good thing is you do not need elaborate equipment like filters or lighting systems to culture algae. Hope this helps.

wah, advice from the expert. thanks!!

just curious, these larvae are attracted to light, if you put the light source at the side of the box, will they "ram" the side of the box till they die?

Next, at which stage should i start feeding them nauplii? after reference to german crab expert beastie (he has successfully reared red claw crabs from eggs to adult before), he feeds his larvae nauplii after 3 days. today is the 3rd day, and these afternoon i just tried hatching some nauplii eggs which i think will be ready tomorrow. Will it be fast enough?

Lastly, in the fishing box setup, i am thinking that there will be no current, and the water may turn stale. Furthermore, with the small amount of water, the larvae will be subject to drastic temperature fluctuations, wont the larvae be severely affected this way?

thank you for your expert advice

thanx unker guqin for the guidance. now lucas we want to see daily pix

haha, will try to update as much as i can

Could you post images of the mother crab so that we can confirm the identification?

ok, will try.

No photo updates, but just a quick summary of the situation. Larva should have about 100-200 left, still feeding phytoplex phytoplankton, feeding them 1 day old nauplii tomorrow. i also added several sea lettuce to help reduce nitrates and ammonia.

[BEASTIEPENDENT]

Hi there

If not, you will have to hatch brine shrimp nauplii everyday until the larvae is large enough to take bigger day-old or bigger nauplii.

Exactly! The description is good in all parts – except we would give nauplii not only if algae are not available but in every case. I think "mixed" food is best for the larvae in any way.

We have here our breeding report in english: http://panzerwelten.de/forum/thread-712.html It's from Pseudosesarma but in general the breeding is the same for all marine and mangrove crabs – whereas of course the mangrove crabs need some land when they grow from megalopa to real little crabs. Maybe You can find here some clues either.

Good luck!



EDIT: Oh, You have answered already in the meantime. Yes, temeprature changes seem to be one of the biggest challenges for the larvae. It seems more important to keep a temperature than to meet the "best" temperature in any case. There are scientific reports either regarding that sensitivity against such changes.

In such tiny compartments as posted above You probably would have to change the water daily – as stated from guqin himself: "You can also make a water change at the same time…" /EDIT

[lucasjiang]

One last thing to add.

Although i am left with 100-200 zoea, the death rate is slowing down drastically. At first i started with 1000-2000 plus, then about 80% death rate from the second to third day, which left me with about 100-200.

now from the third to fourth day, the death rate has stayed low ,about only 20%, still have about 100-200, so i expect that the zoea population will stay relatively stable.

thanks for all the encouragement

[Aquarubies]

I would like to ask if the breeding process for microcrabs be the same as I have 4 microcrabs that constanly hatch larvae but i have yet to raise them up succesfully. I just off the filter in the tank and let it grow by itself,but almost all of them will die in a couple of days. will the microscopic organisms in the water be enough for their survival?

[stormhawk]

They are fed on phytoplex phytoplankton (i was trying to find for liquizell, but to no avail).

Hello lucas,

Firstly, congratulations on the crablets/lings etc. It's an achievement to see so many of them at once.

Regarding the foods, there is a commercially sold item called Liquifry Marine. It's supposedly meant for feeding corals and other marine filter feeders. I used to feed it to my BBS to let them grow a little bigger. It works but care must be taken when feeding the little crabs with this.

As for Liquizell, perhaps ordering it from a seller on eBay might be worthwhile.

[lucasjiang]

Hi there


Exactly! The description is good in all parts – except we would give nauplii not only if algae are not available but in every case. I think "mixed" food is best for the larvae in any way.

We have here our breeding report in english: http://panzerwelten.de/forum/thread-712.html It's from Pseudosesarma but in general the breeding is the same for all marine and mangrove crabs – whereas of course the mangrove crabs need some land when they grow from megalopa to real little crabs. Maybe You can find here some clues either.

Good luck!



EDIT: Oh, You have answered already in the meantime. Yes, temeprature changes seem to be one of the biggest challenges for the larvae. It seems more important to keep a temperature than to meet the "best" temperature in any case. There are scientific reports either regarding that sensitivity against such changes.

In such tiny compartments as posted above You probably would have to change the water daily – as stated from guqin himself: "You can also make a water change at the same time…" /EDIT

thanks, in fact i was making a lot of references from that page already. that page was my greatest help.

I would like to ask if the breeding process for microcrabs be the same as I have 4 microcrabs that constanly hatch larvae but i have yet to raise them up succesfully. I just off the filter in the tank and let it grow by itself,but almost all of them will die in a couple of days. will the microscopic organisms in the water be enough for their survival?

hmm, i have tried raising these, and a lot of other aquarists have. for some reason, they always die after a few days.

Hello lucas,

Firstly, congratulations on the crablets/lings etc. It's an achievement to see so many of them at once.

Regarding the foods, there is a commercially sold item called Liquifry Marine. It's supposedly meant for feeding corals and other marine filter feeders. I used to feed it to my BBS to let them grow a little bigger. It works but care must be taken when feeding the little crabs with this.

As for Liquizell, perhaps ordering it from a seller on eBay might be worthwhile.

thanks, this product i bought is similar to the liquifry marine that you mentioned, it is used to feed corals and clams and filter-feeding animals.

[stormhawk]

The Liquifry Marine does not seem to be a plankton based product, but I don't have the box to get info off right now. It could be a good addition to your current diet of phytoplankton for the babies.

[lucasjiang]

Hi guys, sorry for the disappointment, all the crab larvae are dead. Sorry for disappoiinting all of you. Well, they survived 5 days.

[stormhawk]

Sad to hear that. Good luck on the next round Lucas.

[lucasjiang]

well, as least i gained quite a lot of experience.

[stormhawk]

Yup, and now you have time to source for Liquizell online in preparation for future batches.

[dkk08]

well, as least i gained quite a lot of experience.

That's the spirit Lucas! We should not dwell on failures but instead look at how we can learnt from our failures and mistake and improve on it

To me you've already put Singapore on the map (at least you're the only person known now in Singapore to have breed them till that stage )

WELL DONE!

[lucasjiang]

thanks for the encouragement desmond. actually i already have plans to continue experimenting, not with batik crab larvae (as the batik crabs dont lay eggs often), but with micro crab larvae, which will be easier (as they are freshwater). Hope that i will succeed in the next try.

[BEASTIEPENDENT]

That's the spirit Lucas! We should not dwell on failures but instead look at how we can learnt from our failures and mistake and improve on it

Correct! Our breeding of Pseudosesarma moeschi and Nanosesarma sp. took some 20 trys or so either. There are some factors we cannot guarantee because they mostly are not even known – e.g. some larvae need some special substrate, some special food or the presence of conspecifics to molt into the next larval stage. These are factors we don't even know! So for a succesful breeding You surely need some luck either, not ONLY the correct surroundings for the larvae.