Thai Micro Crab: The Ultimate Guide for Aquarists

If you’re an aquarist looking for an intriguing and low-maintenance addition to your underwater world, Thai Micro Crabs could be your new favorite! As one of the few fully aquatic crab species out there, these tiny critters are both unique and eye-catching.

These little creatures, also known as Limnopilos naiyanetri, False Spider Crabs, or Pill-Box Crabs, easily adapt to various conditions and are quite compatible with many small aquarium setups. However, they do require careful attention to water quality and a peaceful environment.

So, with this intriguing species in mind, let’s learn how to provide them the best possible care so you can enjoy the benefits of these fascinating little crabs in your own aquarium.

Species Overview

Here’s a helpful table with all the essential information you need about Thai Micro Crabs:

Scientific NameLimnopilos naiyanetri
Common NamesThai Micro Crab, False Spider Crab, Pill-box Crab
DistributionTha Chin River, Nakhon Pathom Province, Thailand
SizeUp to 1 inch (2.54 cm)
Lifespan1 – 2 years
DietOmnivore (algae, biofilm, detritus)
TemperamentDocile and peaceful
Minimum Tank Size5 gallons (20 liters)
Temperature75°F – 84°F (24°C – 29°C)
pH6.5 – 7.5
Water Hardness3 – 12 dGH
Care LevelEasy
Filtration/Water FlowLow to moderate
Water TypeFreshwater
Breeding DifficultyModerate
CompatibilityNano tanks, small fish, and invertebrates

With this table, you have all the necessary information to successfully care for Thai Micro Crabs in your aquarium. Remember that they are docile and peaceful creatures, so make sure their tank mates share a similar temperament. Happy fishkeeping!

Thai Micro Crab Basics

Origins and Natural Habitat

Thai Micro Crabs are unique and fascinating freshwater crabs that are only found in Thailand. Specifically, they are endemic to a particular river, making them a rare and captivating species for hobbyists. They were first introduced to the market in 2008 and have since become popular among fish-keepers who enjoy their docile nature and interesting scavenging behavior.

Size and Shape

Small and delicate, Thai Micro Crabs are ideal for nano tanks and other small habitats. With an average size of 0.4 inches in diameter, their thin and semi-transparent legs might make them appear slightly larger than they really are. Males and females have a similar size and shape. However, you can differentiate them by the females’ slightly more rounded bodies. In spite of their small size, these crabs have a circular carapace that resembles larger crab species.

Color and Markings

In terms of coloration, Thai Micro Crabs exhibit a beautiful silvery-gray hue on its body, with warmer, brown-toned legs. They may be sometimes referred to as Thai Micro Spider Crabs or False Spider Crabs due to the length and appearance of their 10 legs. Of special note, these crabs have unique filaments growing from their legs and claws, which they use to capture food particles.


On average, Thai Micro Crabs live for about one and a half years. You can maximize their lifespan by giving them proper care and maintaining ideal water conditions in their tank. As they are peaceful creatures, they make for an enjoyable addition to your aquatic community, spending their time scavenging for food and showcasing their captivating behaviors.

Diet and Feeding

Thai Micro Crabs are omnivorous scavengers that spend their day looking for food. With the hairs on their legs and claws, they capture microorganisms and food particles in the water. Your crab will also happily munch on plant detritus and algae.

To ensure your crab gets proper nutrition, it’s essential to provide daily meals. You can offer them powdered plant-based shrimp food, which is popular among Thai Micro Crab owners. Sinking algae wafers or powdered foods are also suitable options.

It’s important to include protein in their diet, so incorporating live or frozen food like mosquito larvae will be beneficial. A well-rounded diet is crucial for the overall health and nutrition of your Thai Micro Crabs.

Stay consistent with feeding, and monitor their behavior to adjust the diet if necessary. By providing a balanced and varied range of foods, you’ll keep your crabs healthy and happy in your aquarium.

Behavior and Temperament

Thai Micro Crabs are known for their docile, easygoing, and shy nature. You’ll often find them hiding among plants and natural decorations in your tank throughout the day. Don’t worry if they seem inactive or unresponsive at times; it’s normal for these crabs to sit motionless for several hours.

In a peaceful community tank, your Thai Micro Crabs should coexist well with other creatures, as they don’t exhibit aggression towards their tankmates, including those of the same species. However, be mindful of their hiding habits, particularly during the molting process. During this time, these crabs are vulnerable to attacks, as their new shells take time to harden. Providing ample hiding spots for your Thai Micro Crabs will help ensure their safety and give them a sense of security in their environment.

Remember that their activity levels are sporadic, so you might not see much movement at certain times of the day. This is typical for these fascinating little creatures and part of their overall charm. With patience and understanding, you’ll enjoy observing the unique behavior of your Thai Micro Crabs in their peaceful aquatic world.

Care and Tank Requirements

Caring for Thai Micro Crabs is relatively easy, as they can thrive in normal and low-maintenance tank conditions. These crabs adapt well and are not picky about water parameters. However, they are susceptible to major changes in water quality. To provide an ideal environment for your Thai Micro Crabs, consider the following sub-sections.

Tank Size

Thai Micro Crabs can be kept in small tanks, like nano tanks with at least 5 gallons of water. They are fully aquatic and do not require any land area in their tank.

Water Parameters

It is essential to replicate their natural environment with warm water and a neutral pH balance. Make sure to allow the tank to cycle before adding the crabs, as they are sensitive to ammonia, nitrate levels, and chemicals in the water. The recommended water temperature is between 72°F to 82°F, pH levels should range from 6.5 to 8.0, and water hardness should be between 6 to 15 dKH. Regular water testing and changes every couple of weeks are crucial for your Thai Micro Crabs’ health.

Tank Setup and Decorations

Provide natural live plants for foraging and shelter within the tank. Thick vegetation is important for Thai Micro Crabs, so consider adding floating plants such as Java Moss, Duckweed, Water lettuce, and Anubias. You can also include natural decorative items like driftwood and rocks to create hiding spots and enrich the tank environment.

Filtration and Aeration

Using a solid filtration system is essential for maintaining a well-balanced and cycled tank. However, be cautious about strong currents and suction inlet tubes, as Thai Micro Crabs can be vulnerable to them. Utilize foam covers for tubes to prevent the crabs from being sucked into the filter. Remember that these crabs spend most of their time foraging for food, which can come from the plants and various types of aquarium algae in the tank.

Suitable Tank Mates

When choosing tank mates for your Thai Micro Crabs, it’s important to consider their size and vulnerability. These crabs are peaceful and generally get along well with other fish without showing aggression. However, larger fish may see these crabs as prey, so it’s crucial to select small and peaceful species as tank mates.

A good picking would consist of:

  • Cherry Shrimp
  • Kuhli Loach
  • Bloodfin Tetra
  • Cherry Barb
  • Pygmy Corydoras
  • Ember Tetra
  • Most snails
  • Harlequin Rasbora
  • Neon Tetra

Thai Micro Crabs are inherently defenseless, making it essential to prevent housing them with larger and more aggressive fish. To boost their confidence and activity levels, consider keeping them in groups of five or six.

As for compatibility with Betta fish, opinions vary, and experiences differ among aquarists. While some have had success, others have encountered challenges. Therefore, it’s best to carefully assess the risks involved and determine whether it’s worth attempting to house Thai Micro Crabs with Betta fish in your aquarium.


Breeding Thai Micro Crabs can be quite a challenge in captivity, even though there have been a few successful attempts. When it comes to breeding, female crabs do have the ability to carry and release eggs, and some may even hatch. However, you’ll likely encounter difficulties in keeping the baby crabs alive after hatching.

The mortality rates for these baby crabs are typically high, leading to difficulties in achieving successful breeding. As a friendly reminder, you should be prepared for such outcomes if you decide to try breeding Thai Micro Crabs. Many breeders are actively undertaking experiments to find ways to improve their survival rates.

For now, due to the lack of a reliable method, it might be best to avoid attempting to breed Thai Micro Crabs. Instead, focus on providing proper care and maintaining a suitable environment for the adult crabs to thrive in your aquarium.

Common Diseases and Treatments

Thai Micro Crabs, similar to other freshwater crabs, can suffer from bacterial and fungal infections. A major cause of illness in these crabs is general body stress, which often relates to water quality. Therefore, maintaining high water quality in your tank is crucial for keeping the crabs healthy and reducing the risk of disease.

Although the specific diseases that Thai Micro Crabs can suffer from are not well-known, monitoring their health and behavior is an essential aspect of detecting potential issues early on. If you come across dead-looking crabs at the bottom of the tank, do not be alarmed. These might actually be molted shells, as Thai Micro Crabs molt regularly. Molting is a healthy process for these crabs, where they shed their carapace to grow larger. In such cases, it is important to examine the molts closely to determine if the crab is truly deceased.

Research and observation on Thai Micro Crabs are ongoing, leading to a better understanding of their specific diseases and health conditions. Keep a friendly and attentive approach towards these fascinating creatures, as it will help ensure their well-being in your tank.

Frequently Asked Questions

How big do Thai micro crabs get?

Thai micro crabs (Limnopilos naiyanetri) are very tiny creatures that live up to their name. They typically grow up to a size of 1 to 1.2 cm across their carapace. Due to their small size, they are perfect for nano tanks and small habitats.

Can Thai micro crabs live with shrimp?

Yes, Thai micro crabs can live with shrimp. In fact, they share relatively similar care and requirements to those of dwarf shrimp. Both species are docile and enjoy scavenging for food together, making them ideal tank mates in a peaceful and well-maintained aquarium.

Can Thai micro crabs live with guppies?

Thai micro crabs can potentially coexist with guppies in an aquarium. However, be cautious about keeping them together, as guppies might prey on the tiny crabs. To avoid this, provide plenty of hiding spots, like plants or decorations, where the micro crabs can retreat and find refuge.

Do Thai micro crabs eat snails?

Thai micro crabs primarily scavenge for detritus and microorganisms such as biofilm and algae. While they might eat snail eggs or tiny snails if they come across them, they do not actively hunt or feed on larger snails in the aquarium.

Do Thai micro crabs eat algae?

Yes, Thai micro crabs enjoy eating algae in their diet. They play the role of efficient scavengers in your aquarium, helping to keep the algae levels under control by feeding on it. This can help maintain a clean and healthy environment in your aquatic habitat.