Limnopilos Naiyanetri (Thai Micro Crab)

[Urban Aquaria]

Finally got the opportunity to get my hands on a group of Limnopilos Naiyanetri... aka Thai Micro Crabs!



These are some of the more unique crabs available that are fully aquatic. Add to the fact that they stay very tiny in size (only around 1 cm in length, excluding their legs), these micro crabs make for very interesting inhabitants in smaller tank setups.

Just for scale comparison... here is one resting on my palm.



They seem to be quite capable of traversing across dry "land", i guess in nature they can crawl around to different water sources in search of food and shelter.

While i was in the midst of transferring them to my main tank, one hopped off the net and started to scuttle around my hand.



When newly introduced into a tank (after a suitable period of drip acclimation), they tend to exhibit a pale transparent coloration.



Once they adapt to the tank environment, their original brownish colors gradually return, though i noticed that they will still switch between colors depending on mood and also to match their surroundings.

So far, i've only caught brief glimpses of them in my tank. Once they disappeared into the plant growth, i've not been able to get a good photo of them yet... thats one of the considerations when keeping micro crabs, they are tough to observe in planted tanks!

Can you spot the micro crab hiding inside this clump of Anubias sp. "Petite"?



They spend most of their time moving between dense plant growth while scavenging for food, i've seen them actively picking along the surfaces of plant roots and leaves, they also graze on algae wafers and blanched zuchinni too. It seems they are quite similar to cherry shrimps in terms of diet and care.

Overall, they are interesting additions to an aquarium... though if you have a layout with lots of hardscape and plants, chances are they will tend to be hidden most of the time.

[Clamence]

Nice, did not get a chance to spot them at c328 today. I only saw panther crab and some species of aquatic crab with red claws and very small sized. Their eyes are also protruding upwards like a fiddler crab, any idea what species it could be?
May i know how big is your tank and how many crabs you got? Thinking of getting some but afraid that they may kill each other

[Urban Aquaria]

Nice, did not get a chance to spot them at c328 today. I only saw panther crab and some species of aquatic crab with red claws and very small sized. Their eyes are also protruding upwards like a fiddler crab, any idea what species it could be?

Yeah, i only chanced upon them while looking though the bags of shrimps, happened to pick out a bag from the back row and looked closely... discovered they were full of thai micro crabs.

I'd guess those crabs with red claws could probably be Perisesarma Bidens? Apparently those types still need some land area though.

May i know how big is your tank and how many crabs you got? Thinking of getting some but afraid that they may kill each other

I put them in a 2ft tank, so far it seems they are quite peaceful and don't fight... maybe because there is enough space and food sources for all of them to co-exist.

Though when i selected my micro crabs from the LFS bag, i did notice some of the crabs were missing claws and legs, so it could be possible they might fight if kept really crowded in very close proximity conditions.

[Urban Aquaria]

...and how many crabs you got?

I got 5 micro crabs... i guess there is quite alot of space in the 2ft tank for them.

[Dscheng]

how much u brought it? A bag?

[Urban Aquaria]

how much u brought it? A bag?

They were S$8 each at C328.

I didn't buy the entire bag of them... i just hand-picked a few of the larger ones.

[skytan]

Very cute crabs.
was looking at them at a LFS they will dig and hide inside the empty substrate almost didn't notice their camo

[Urban Aquaria]

Very cute crabs.
was looking at them at a LFS they will dig and hide inside the empty substrate almost didn't notice their camo

Yeah, they need objects or plants to cling on to and ample places to hide... in open layout tanks without much plants (ie. LFS retail tanks or shrimp breeding tanks), i noticed they will tend to panic and try hiding inside the substrate.

I was reading up on them and it seems they come from a river in thailand, where they are found clinging deep inside the dense feathery roots of water hyacinths. I guess thats how they naturally survive in the wild, by effectively hiding from predators and feeding on microfauna/zooplankton that also live amongst the plant roots.

[lucasjiang]

These crabs can survive in rather high densities. The most I kept was about 10 in a 1 ft tank. What is crucial is to fill the tank with vegetation.

They lose their legs and pincers most likely because they have a tendency to cling to each other in a ball when they have nothing to hold on to. Then they end up nipping each other.

[ZIr]

These crabs seem to be everywhere now. Saw them at AA yesterday, hiding in substrate, GC and Y618 also updated their FB pages with them. Seems like season in for these critters?

[Shadow]

Interesting, would they un-root plant like CPO (Orange Dwarf Crayfish)?

[lucasjiang]

Interesting, would they un-root plant like CPO (Orange Dwarf Crayfish)?

It won't, but for newly planted carpet plants like glosso and monte carlo, it might uproot those.

[Urban Aquaria]

Okay, some observations... after checking all the nooks and crannies in my tank today, i managed to find all 5 of them hiding together inside the same bunch of plant roots. Interestingly, the exact location they are hiding in is shaded from everything (i can barely see them through the dense roots) but its directly in the path of the lily pipe's return flow. Shrimps that walk past that area will usually get blown back by the force of the filter flow, yet the micro crabs position themselves there, clinging on tightly to the plant roots.

The odd thing is i deliberately placed them separately in all corners of the tank during initial introduction into the tank, yet they all still converge and end up sitting in the same location. I guess they are attracted to all the bits of food particles that drift through that area. I could see their tiny claws continuously picking at the hairs on their carapace and legs, presumably the hairs help trap micro food particles which they feed on.

Only problem is the location they are all comfortably holed up in is totally hidden from view, so if this carries on, i will hardly get to see them at all!

Now i regret putting them into a planted tank.... i'm probably going to transfer them to a dedicated nano tank soon (maybe with just lots of java moss so that its still easy to observe them). Luckily my existing plants are the non-rooted types so its abit easier to get them out, i shudder to think if it was a tank with rooted plants and dense carpet.

To anyone who is reading this thread and thinking of putting them into a planted tank, don't do it! Setup a dedicated tank for them and keep them there instead.

[blu3her0]

Nice write up! I just bought 7 of these, and I can only spot 1-2 at a time. Densely planted tank though, so you're right UA. 🏻Attachment 48515

[uglyduckling]

You mean 8sgd is for 1 bag or 1 crab?
Do they have a lot of these, maybe I'll visit there this weekend to find some. They looks cute


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[Urban Aquaria]

You mean 8sgd is for 1 bag or 1 crab?
Do they have a lot of these, maybe I'll visit there this weekend to find some. They looks cute

It was S$8 for each thai micro crab... not sure if the LFS still have stock, i guess you'll just have to visit them to check.

[Francis247]

So far from my observation, my 3 micro crabs like to cling on to the Sulawesi rocks and hide there.
They prefer dark places I guess.

[uglyduckling]

Any specific requirement for this crab? Do they need cool temp? I dont have chiller or fan, temp range is around 28-30C daily, is it ok?
8$ is kinda expensive


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[lucasjiang]

Any specific requirement for this crab? Do they need cool temp? I dont have chiller or fan, temp range is around 28-30C daily, is it ok?
8$ is kinda expensive


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Dont worry your temperature is fine, these crabs are really hardy.

[Phillipians]

Wow $8 for a micro crab? Hmmm that is quite expensive but certainly not in the range of some shrimps haha.
No wonder AA staff told me they were getting a tank ready for some very interesting fauna. I only have time to visit on a weekend so hopefully can pop by get 2 to 3 for my 1 ft cube tank...