Thai Micro Crab – Limnopilos naiyanetri: Care Guide

The Thai Micro Crab is one of our favorite aquatic creatures of all time! They are quite under the radar, but we recommend them to other aquarists all the time.

This is why:

This is one of the lowest maintenance crab species you can own. They can thrive in a wide range of conditions that most aquarists are familiar with.

They look great too! These tiny creatures are quite different from most of the species you see other aquarists possess. It seems that they are from another planet!

This guide will teach you everything you need to know about Thai Micro Crab care and the species in general. We promise you’ll consider getting some by the time you’re done reading!

Species Summary

Perfect for nano tanks and small habitats, the Thai Micro Crab (Limnopilos naiyanetri) really lives up to its name. These crustaceans are some of the smallest you can get your hands on! They are very docile and can be a delight to watch as they forage for food.

These freshwater crabs can only be found in one place in the world. They are endemic to a specific river in Thailand, hence their name. The Thai micro crab is sometimes referred to as the Thai micro spider crab or the false spider crab.

The tiny creatures are relatively new to the aquarist community, having been introduced to the market in 2008. However, that hasn’t stopped aquarists from buying them in droves! There are still many unknown things about this species. Fortunately, the basic care requirements have long been established.

Life expectancy

The normal shelf life of Thai Micro Crab is around one and a half years when healthy. These little creatures do not live long.

It’s worth noting that this average is for crabs kept in a well-maintained environment. Do not make this species think that it can exceed this by giving them great care.

Author’s Note: Because these creatures are so small, they are very susceptible to changes in water conditions. To keep them healthy and maximize their lifespan, you need to be vigilant about maintaining your tank.


If you are lucky enough to get a close-up view of Thai micro crabs, you may be surprised to find that they are very similar to their larger counterparts. They have a circular shell, which is the main body of the crab.

Usually these crabs are silver-gray in color. Legs may take on a warmer brown hue. You can also see a slight transparency on her legs.

These crabs are often mistakenly called spider crabs, and it’s not hard to see why.

Its 10 legs are very long compared to the rest of the body. When fully extended, its size increases significantly.

However, most of the time they spend with their legs tucked under their bodies. An interesting thing about Thai micro crabs is the filaments that grow on their legs and claws.

These hairs are meant to capture food particles in the water. They can grab microscopic snacks, which helps tremendously when they are looking for food.

For the most part, there is not a size difference between males and females. However, you can easily identify the females thanks to their rounded bodies. Males tend to have narrow, somewhat pointed shells.

Average size

The average size of a Thai micro crab is only 0.4 inches! This is the diameter of their shell, which is how the size of crabs is measured.

As you can see, these creatures are quite small. Nevertheless. the size of their legs can make them appear slightly larger.

Despite this, it can be difficult at first to locate them in your tank (it will get better with practice). You see, the slim, semi-transparent nature of the legs doesn’t do much to improve visibility.

Thai Micro Crab Care

Thai Micro Crab care is a piece of cake. One of the main reasons this species has become so popular is that they can thrive in very normal, low maintenance tank conditions.

They are not like other crab species that may require adjusted temperatures or brackish water.

Thai Micro Crabs can adapt very well and are not fussy about parameters. Of course, these creatures are susceptible to major changes in water quality. The key is to keep your tanks stable while providing them with a high quality food source.

Here are the essential care guidelines you should follow:

tank size

Starting with the tank itself, these crabs don’t need a lot of space. At less than half an inch in size, it can keep a group in a relatively small tank.

These crabs are ideal for nano tanks that can hold at least 5 gallons. A small group of five or six crabs will have no problem thriving in such a small tank.

However, Thai micro crabs will need a slightly larger tank if you plan to keep them with fish (more on that in a bit).

Author’s note: One good thing about this species is that it is completely aquatic. There is no need to worry about creating a piece of land. They will spend their entire lives below the surface of the water.

water parameters

As with any aquatic creature, the best way to keep these crabs healthy is to replicate their natural environment as much as possible. All of this starts with the water. Fortunately, that’s not hard to do.

These crabs come from a single river in Thailand. The tropical environment is relatively easy to reproduce in a freshwater tank. All you need is warmer water and a neutral pH balance.

Once you have established the tank, give it some time to pass before adding the crabs. Thai micro crabs are sensitive to ammonia and nitrate levels. They can also be affected by chemicals in the water.

Giving the tank some time to mature will ensure that it is safe and ready for these crabs.

Follow these water parameters and your Thai micro crabs should have no problem staying healthy.

  • Water temperature: 72°F to 82°F (somewhere in the middle of this range is ideal)
  • pH levels: 6.5 to 8.0
  • Water hardness: 6 to 15 dKH

It’s also important to test your water regularly (especially early on). Water changes every two weeks are also essential.

What to put in your tank

When it comes to decorations, a natural setting is always better.

While you can use plastic tank accessories, Thai Micro Crabs do need some real organic matter to stay healthy. These crabs spend most of their day foraging for food, and that has to come from actual, live plants.

Thick vegetation is important. The river that the Thai micro crabs come from is very dense. Most of the time, crabs can be found living on the roots of those plants.

Decorate your tank with floating plants. You can try Java Moss, Duckweed, Water lettuce and Anubias. Introduce as many plants as possible. Not only are they a food source, but the plants will also act as shelter.

You can complement the plants with natural decorative elements such as driftwood and rocks. These are excellent places for aquarium types of algae to accumulate, which are also eaten by Thai micro crabs.

To keep your tank looking good and in good shape, you’ll need a solid filtration system. However, these tiny crabs are very vulnerable to strong currents and suction intake tubes.

Be sure to use foam covers for the tubes to ensure that the crabs are not sucked through the filter.

Possible common diseases

Not much is known about the diseases that Thai micro crabs can suffer from. Currently, there are no specific ailments of the disease.

With that said, they can suffer from all the safe bacterial and fungal infections that other freshwater crabs experience.

The most common cause of any crab illness is actually general bodily stress. Stress is directly related to water quality. As long as you maintain the water conditions, you should have no problem keeping the crabs healthy.

Author’s Note: You may witness what looks like a dead crab at the bottom of the tank. Before you take it out, examine it closely. Most likely it is a molted shell.

Thai Micro Crabs molt like any other crab. They shed their shell as they grow, leaving behind a hollow shell. This is perfectly normal and healthy.

Food and Diet

Thai micro crabs are natural omnivores. As we mentioned earlier, they will generally forage throughout the day. Using those hairs on their legs and claws, crabs capture microorganisms and food particles that float through the water.

You may also see crabs feeding on plant debris and algae.

While they can get much of their daily nutrition through garbage, you also need to provide them with daily meals. A popular choice for aquarists is plant-based powdered shrimp food.

You can also try sinking algae wafers or powdered foods that are small enough for shrimp to consume.

Some proteins are also crucial for this species. You will need to provide some hearty live or frozen foods, such as mosquito larvae.

behavior and temperament

Thai micro crabs are very docile and tolerant. They are shy by nature and often spend most of the day hidden among plants and natural decoration.

They show no signs of aggression towards other creatures. This includes tank mates of the same species!

As a result, they are ideal for peaceful community tanks.

This species is also very sporadic when it comes to activity. Don’t be surprised if you don’t see much movement from your Thai micro crabs at random points throughout the day.

These crustaceans are known to remain motionless for several hours. If you can’t see them at all, they are probably hidden.

Hiding is very normal for these crabs. It is more common at the time of moulting. When they molt, Thai micro crabs are incredibly vulnerable to attack because their new shells take time to harden.

tank mates

There are some special considerations to keep in mind when choosing tank mates for the Thai Micro Crab. They do well with other fish and will not show any signs of aggression.

But it’s not crab aggression you have to worry about.

These critters are the perfect snack size for large and medium fish. They will be instantly eaten by any fish that is larger than them. As such, they should only be kept with small peaceful species.

Remember, these crabs are practically defenseless. You should never take a chance and house them with larger fish that can eat them.

It is also important to keep several Thai micro crabs together. They do very well in groups of five or six. The crabs will feel more secure and will generally become a bit more active in the presence of others.

Here are some good tankmates to consider:

Author’s Note: Many aquarists ask about the possibility of Thai micro crabs being kept with betta fish. The answer is not very clear, as there are some aquarists who have had success with this combination and others who have not.

Understand that there will be an element of risk if you really want to try this out. Personally, we don’t think it’s worth it.

Thai Micro Crab Breeding

Unfortunately breeding Thai Micro Crab is quite difficult in captivity even though it has been accomplished before. In fact, many crabs will reproduce on their own.

The problem comes with keeping the baby crabs alive.

Many aquarists will observe their female Thai Micro Crabs carrying and releasing eggs (some even hatch). Unfortunately, babies almost always die before they can grow.

Breeders continually experiment to improve mortality rates. Until an established method emerges, we recommend that you avoid trying to breed these crabs.

What do you think?

We hope this guide has not only educated you on the basics of Thai micro crab care, but also encouraged you to give this species a try.

We have heard many aquarists swear they will always keep some in their freshwater tanks. These little critters really grow on you!

If you want to learn more about this species or just have questions in general, give us a shout. Any new opportunity to talk with a fellow aquarist is always welcome.

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