Thai Micro Crab larvae??

[Bern C]

Saw quite a numbers of white & brown dots floating in my tank this morning. At first I though that I accidentally introduced some Daphnia in the tank but later realized it's not. I guess it's probablly TMC larvae?
Any idea how to take care of them?? I read that breeding them is very very difficult.


@_@ Sorry for the poor quality.

[Bern C]

A closer look.



I think it should be TMC larvae as compare to this magnified view of TMC larvae. https://www.youtube.com/watch?v=sWAdJiJjVFk

[Urban Aquaria]

Their movements do seem to resemble micro crab larvae... if you have a group of micro crabs in the tank, then i guess chances are those are crab larvae.

Its a good idea to get a clip-on macro lens for your phone camera, then you'll be able to take close up photos and videos of the larvae in much greater detail to confirm its identity.

My current batch of thai micro crabs did hatch larvae initially when i got them (2 of the female crabs were already berried from the LFS), a few weeks after introduction into my tank they hatched the larvae and i also saw tiny dots swimming around the tank. Unfortunately the tank had a hang-on filter running in it and the sponge guard was probably not dense enough, so most of the larvae got drawn into the filter and the rest didn't survive (at that time the tank was still a new "clean" setup and i couldn't supply suitable food for them in time), so none managed to develop into the crab stage.

I'd assume that ample concentration of suspended food particles and algae would help feed the larvae, so perhaps you can try adding some powdered foods and leaving your tank lights on for longer period to boost algae growth. Other than that i guess you'll just have to wait and see if the larvae manage to develop further.

Looking forward to see your updates!

[Bern C]

Hi shifu UA,

No luck in breeding them. On the 2nd day, 60% of the floating larvae went missing but I do saw some grew in size. Then on the 3rd day, no more floating larvae but I found some on the sponge filter when I was doing WC and maintenance. I gently squeeze and rinse the sponge in transparent container and found 8 larvae still surviving at the bottom of the container. The larvae no long floating but staying at the bottom jerking. Then I pour the larvae back into the tank.

I just started keeping TMC. I got 10 of them 2 months ago but left with 6-7. 3 of them confirmed dead with bodies found while 1 MIA dunno hiding or dead. The 3 of them died during the 1st 2 weeks and 2 of them died with abdomen opened.
@_@ When I was buying them I got ask the shop keeper if able to tell the sex but he said hard due to the size. So he randomly picked 10 for me. Most of the time they were hiding but a few times I did manage to take a look at the abdomen and found some of them are different. Do the male and female have different size?? I realized some of them haven't been growing much while 3 of them grew 1.5x larger than the rest.

It's only recently I saw the larvae as I got a new tank dedicated to them. Initially I was keeping them in a tank with a guppy & some rasbora. @_@ so probably the spawning will be food for the fish. Then 1 weeks+ ago I transferred 2 big 1 small TMC into the new tank with some commando RCS which used for cycling.

=( Don't have a clip on lens so can't take a magnified pic. I tried to use a magnifying glass and saw the tail keep wiggling around. I tried to feed them some yeast on day 1 & 2 but I think the yeast also killed 2 of my commando shrimps. I add 10ml of diluted yeast solution in the afternoon on day 1 and I found a dead shrimp in day 2 morning and same for the following day. So i stopped. Never encounter any death in that tank before and the shrimps are there for 4 weeks.

What do you usually feed your TMC?? I seldom saw mine eating yet they still growing while a few doesn't grow much. After realizing they do not eat much and not interested in shrimp pellet, I stop feeding them and let them eat left over fish micro pellet. I also realize TMC like to eat their own legs hairs, XD they are filter feeder? I always saw them sticking their legs out then later pulling something from their legs and put into their mouth.

[Urban Aquaria]

Differentiating their gender seems to be similar to most other crabs, the females should have wider flap at the bottom, while males have narrow flap, but it's difficult to see due to their tiny size... the other simpler method some keepers use is to observe their claw size, apparently the females tend to have smaller claws, while the males tend to have noticeably larger claws. Not sure how accurate that is though.

Yeast solution could be used to feed the hatched larvae, it's a live fungi culture and is usually safe with inverts (i use it to feed my daphnia moina cultures and shrimplet grow-out tanks whenever i run out of green water), so maybe it might just have been a coincidence that one of your shrimps died. Anyways, you could also try other particulate foods like spirulina powder, hikari first bites or liquifry.

The thai micro crabs i keep seem to just graze and pick on algae and bio-film that coat my tank's plants, hardscape and substrate... like what you observed, they are also able to trap and catch floating food particles in their limb hairs and pick on those to get food too.

I do occasionally spot them grabbing broken bits of food pellets that managed to drift past my fishes and shrimps, so they do eat commercial food if it's available. They have extremely low food requirements though (due to their tiny size), so they actually don't eat much anyways, hence i also don't feed them specifically too, since i'm already feeding other livestock in the tank.

[Bern C]

I see... didn't know can tell from the claw. I will try look at the claw. I think looking at abdomen flap will be the best. Initially can't tell as they were very small but as the grew larger it's easier. I saw some of them with wider and rounder and the dead one also.. @_@ the whole flap opened. I was like o.O what happened.

I have been using the same pack of yeast that I feed my daphnia daily but nothing happened to my daphnia. @_@ So not sure what happened. That packet of yeast have being opened for like a month but kept in fridge. XD Hope it's not expired. I was thinking if it's possible that the fungus choke the grills or something. I doubt it release too much CO2 and deplete the O2 as I used like 5-6 grain of yeast and using sponge filter. I tried added 3ml of yeast solution again and see if anything happen tomorrow.

I tried feeding them shrimp pellet.. dropped 1 near them and one of them seem interested and grab it but after 1min it drop it and move back to driftwood hiding. Few hours later it still there. @_@ I tried this 3x same thing happen. So I just don't care about them and just feed my fish. While the new tank I just feed my commando shrimp. I think the new tank also have many bio film as my shrimp eating lesser and lesser pellets. They keep grazing on the driftwood & Indian almond & sand.
^_^ Glad to heard that my TMC isn't behaving strangely.