Thai Micro Crab (Limnopilos naiyanetri): Ultimate Care Guide


Common NameMicro Crab
Scientific NameLimnopilos naiyanetri
Temperature72-82° F
Water PH6.5-8.0
Water Hardness6-15 DkH
Maximum Size0.5 inches
Minimum Tank Size5 gallons
Food & DietOmnivores
Lifespan1.5 years
Compatible Tank MatesCherry Shrimp, Neon Tetra, Betta Fish
TemperamentPeaceful

The Thai Micro Crab (Limnopilos naiyanetr), also known as the False Spider Crab, is a tiny, fully aquatic, crustacean! A fully aquatic organism is one that spends its entire lifespan submerged under water.

Thai Micro Crabs were first discovered in 1991. They are endemic to Tha Chin River in the Nakhon Pathom Province of Thailand. To date, Tha Chin River is the only body of water where these tiny freshwater creatures have been found. There, they inhabit  the roots of river plants called hyacinth.

False Spider Crabs entered the fishkeeping scene in Germany circa 2008. Since then they have become popular among aquarists specializing in nano-tanks. Thai Micro Crabs have a peaceful temperament and thrive in small spaces. They are considered moderately difficult to care for and are an ideal investment for intermediate aquarists.

Thai Micro Crab
Thai Micro Crab (Limnopilos naiyanetri)

Thai Micro Crab Appearance and Molting

Like their name suggests, “False Spider Crabs” resemble spiders! Instead of eight legs, these  little guys have ten. Each leg is long, thin, and outfitted with tiny bristles. Thai Micro Crabs use these bristles to filter loose organic matter out of the water for food. 

These organisms are extremely small! In fact, a grown Thai Micro Crab will reach no more than half an inch in diameter!

The Thai Micro Crab is guaranteed to be a unique and exciting addition to your freshwater tank. Their alien-like features make them stand out from their fellow tank mates. These crabs are usually a subtle brownish-beige tint. Their colors may vary with some manifesting hues of orange and light gray.

Thai Micro Crabs molt their exoskeletons. They will not molt as frequently as other crustacean species due to their tiny size and slow growth rate. However, the process is the same.

Molting begins when crabs fill their carapace with water. The pressure from the water in the carapace will break open the exoskeleton. Eventually, the crab will shed its carapace and a new one will form beneath it.

Following a molt you may find that your crabs’ bodies will be soft and mushy. They may even appear translucent. Over several days their body will harden and their shedded skeleton will drop to the bottom of the tank.

Molting is a  taxing biological process. It may cause your Micro Crabs to feel stressed. During this time it’s a good idea to keep tank conditions consistent. Do your best to avoid excess cleaning or moving aquarium decor around. If your crabs are acting shy-don’t worry! It is common for molting animals to hide.

Thai Micro Crab Care

The Thai Micro crab is not a demanding aquatic creature to care for. Their dietary needs are fairly straightforward and they get along well with other peaceful species.It is important to note however that these organisms are very sensitive to water conditions.

It is paramount that you test the water in your Thai Micro Crabs’ tank frequently. You should be extra careful about regulating nutrient levels like nitrates. Additionally, you should expect to change your crabs’ water every several weeks.

A good filtration system will help keep things balanced in the interim. Just be wary of filters that simulate strong currents. False Spider Crabs are so tiny that they can easily be swept away into the filter tubes and valves.

With an effective filtration system, a colony of 5-6 crabs can be content in a 5 gallon tank. Buying a larger aquarium may be a rewarding choice as it will make stabilizing the water quality and conditions easier for you.

Your tank should have a PH between 6.5-7.3. Water temperature in the aquarium should be maintained between 70-82. Water hardness levels should be between 6-15 DkH.

Thai Micro Crabs prefer natural tank decor. A large portion of their diet comes from foraging for organic matter. This means that incorporating live plants in their ecosystem is essential. Java Moss, Water Lettuce, Anubis’s and Duckweed are all great options. You can vary the vegetation by mixing and matching floating plants with long stemmed ones. Live vegetation will double as food and shelter for your crabs.

Finally, loose driftwood, rocks and some aquarium algae can be added to the bottom of the tank.

Thai Micro Crabs are known for their nocturnal activity.  If you feel inclined, you can invest in  a night-glo bulb for your aquarium. This way you can watch the crabs move about when the lights go off!

Thai Micro Crab Tank Mates

Thai Micro Crabs are docile and shy. They will spend a large portion of the day hiding. They do not exhibit aggressive behavior towards other organisms which makes them a perfect addition to a peaceful tank ecosystem. As mentioned previously, Thai Micro Crabs will feel most secure when housed in groups of five or six.

 Be sure that their tank cohabitants are also of small and peaceful species. Cherry Shrimp can make for great tank mates. Kuhli Loach and the Neon Tetra are also safe. Betta fish won’t be problematic either.

Alternatively, avoid housing Thai Micro Crabs with aggressive organisms like Cichlids or Angelfish. These fish will mistake your crabs for food.

Thai Micro Crab Food & Diet

Thai Micro Crabs are omnivores and scavengers. In the wild they feed off of plants and small larvae. They filter plant matter out from the water using the bristles on their legs. but it is possible that you will see them feasting directly from the vegetation in their tank too. This is healthy and normal!

Supplementing the Thai Micro Crabs’ scavenging diet with more regular meals is highly recommended. You can feed these crabs store bought food. They are not picky eaters.

For optimal nutrition you should try experimenting with a plant-based shrimp food from the pet store. Or, for a more protein rich option, you can purchase mosquito larvae.

Thai Micro Crab Disease

There isn’t a wealth of information regarding diseases impacting Thai Micro Crabs. However, like all animals in captivity, they can suffer from bacterial and fungal infections.

The small size and fragility of these crabs can make them susceptible to sickness. This is most often caused by poor water quality in their tank.The most important tip for Thai Micro Crab owners is to minimize stressful stimuli inside the aquarium. Stress for these organisms directly correlates to illness.

Thai Micro Crab Breeding

Despite being relatively easy to care for, Thai Micro Crabs are an incredibly challenging organism to breed. In fact, there is yet to be a documented case of an aquarist successfully breeding these crabs in captivity.

Experimental breeding methods are currently being researched. Until then, it is not recommended that you attempt to breed these animals. Nor should you expect for them to reproduce.

Upon first glance it can be hard to distinguish male Micro Crabs from their female counterparts. But, if you take a closer look with a magnifying glass you will see distinct differences. For example, both male and female Micro Crabs have a flap on the bottom of their body.  The female’s flap is wider while the male’s is slimmer. Females also have a more rounded body while males tend to have pointy carapace.

It is possible that you will observe your female crabs carrying and releasing eggs. On some occasions the eggs will even hatch. However, the baby crabs will not last long at all.

Generally, The Thai Micro Crab’s life is a short lived one. In captivity you can expect healthy adults to live only 1.5 years.

Where to Find Thai Micro Crab for Sale

Due to the novelty, and relative scarcity of these organisms, it can be challenging to track the Thai Micro Crab down for purchase. Unlike some of their more common tank mates, you may have trouble finding these in your local pet shop. There are several online sites where you can order Thai Micro Crabs.

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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