Thai Micro Crab

a close up of a thai micro crab hanging onto an aquatic plant looking for food

Are you looking for a new fish to add to your family aquarium? If so, you may want to consider Thai Micro Crabs! These tiny crustaceans are becoming increasingly popular as family pets, and they make an excellent choice for beginner owners.

Thai Micro Crabs are native to Thailand and are known for their small size. They are found in a freshwater river in Thailand. They are smaller than most crabs, only growing to about 1 inch long. They typically measure between one and two centimeters in length and come in a variety of colors, including red, blue, and yellow.

Thai micro crabs are very hardy, and are able to live in a wide range of temperatures. One thing that they do need is some hiding places from fish that can get aggressive with them.

Thai micro crabs are very small, and take up very little space in an aquarium. Thai micro crabs are very easy to care for, and will eat almost anything you put in their tank. They can be fed frozen foods, or fish flakes and they will happily eat it. They will even eat algae, everything they eat reduces the waste in your aquarium.

They are very peaceful, and will not bite or harm anything in their aquarium. Often when they need to hide from an aggressive fish they can be seen hiding in groups.

They are also relatively inexpensive, costing around $5 per crab.

Thai Micro Crabs are social creatures and do best when kept in groups. They can be housed with other small fish, such as guppies or tetras, but should not be kept with larger fish that may try to eat them. They are also very active and love to explore their environment, so make sure you provide plenty of hiding places and decorations for them to explore.

Overall, Thai Micro Crabs are an excellent choice for beginner owners. They are easy to care for and require minimal maintenance, and they can be kept in groups with other small fish. Plus, they are incredibly fun to watch as they explore their tank! If you’re looking for a new pet to add to your family, Thai Micro Crabs are a great option.

Thai Micro Crab Information

  • Average Length: Up to 1 inch
  • Colors: Brownish-Gray, Brownish-Orange
  • Attention Needs: Low
  • Tolerance to Heat and Cold: Yes
  • Good Pet: Yes!
  • Good with Other Crabs: No
  • Good with Other fish species: Only with non-aggressive species
  • Good for Less Experienced Pet Owners: Yes
  • Health Concerns: Intestinal nematodes and Mycobacteriosis
  • Average Life Span: 1.5 years

Thai Micro Crabs are only found in a river called Tha Chin in Thailand. They were first discovered in 2008 and are relatively new to the freshwater aquarium hobby.

Physical Appearance of Thai Micro Crabs

a thai micro crab holding onto an aquatic plant to get to some food

Thai Micro Crabs are not very colorful. They usually are a brownish-gray but some may be brownish-orange or gray.

Thai Micro Crabs are one of the smallest freshwater crabs in the world. The width of their carapace (the hard upper shell of the body) is less than half an inch. They have thin and spiny legs with a width of about 1 inch. Their small bodies and long legs make them look like underwater spiders. Because of their appearance they are often referred to as ‘False Spider Crabs.’

Their entire body and legs are covered with small bristles that help them catch food particles floating in the water.

Temperament of Thai Micro Crabs

Thai Micro Crabs are shy and docile. They spend most of their time hiding inside tank decorations and areas that have a lot of algae. They are not very active and usually come out only at night.

Thai Micro Crabs are one of the few truly aquatic crabs, crabs that can spend their entire lives underwater. For first-time crab owners, them being fully aquatic is great because they don’t have to create a dry surface inside their aquarium.

These crabs are not aggressive and can be kept in small groups. Males of several crab species are known to fight with each other but Thai Micro Crabs are social and live peacefully in groups.

They are completely defenseless and will try to escape or hide when threatened.

Best Habitat for Thai Micro Crabs

a close up of a thai micro crab

Compared to other crab species, Thai Micro Crabs are relatively easy to care for. They are small and don’t need to be kept in a large tank. Because they are fully aquatic crabs, they don’t need dry land inside their tank.

It’s important to keep their tank secured otherwise your Thai Micro Crabs may escape. Crabs are good at climbing and using a mesh top or a net can keep your crabs from climbing out and escaping.

Tank size

A 5 gallons tank is large enough to keep a colony of 5 to 6 Thai Micro Crabs but more space is always better. Maintaining stable water conditions in a small tank can be difficult. Thai Micro Crabs can’t tolerate poor water conditions and keeping them in a larger tank is preferred.

If you plan to build a community fish tank then a larger tank will be needed.


Thai Micro Crabs need a temperature kept between 70°F and 82°F.

Water Hardness and PH

The pH should be between 6.5 to 7.5 and water hardness between 6 to 15 dKH.


These crabs don’t like high lighting. They like to live around darker regions in the tank where they can hide and feel secure. If you plan to use regular aquarium lighting then adding lots of bushy plants will help create a darker bottom in your aquarium. Other popular options are to use inexpensive LED lights and keep them on a dim setting.

Tank Substrates

Thai Micro Crabs spend most of their time hiding in plants and decorations, and don’t need any particular substrate. Any type of shrimp compatible substrate will be good for them.

When deciding on a substrate using one that contrasts with their color will help you see them. Because of their size, and how they enjoy hiding it can often be difficult for you to spot them.


Crabs need a lot of hiding places inside their tank. Hiding places can be created by adding decorations like plants, rocks, caves, treated driftwood or seashells.

Thai Micro Crabs specifically like dense freshwater plants that can give them hiding spaces. They like to hold onto the plants because their natural environment has moving water and they need to hold the plants to not get pushed down river. Mosses, Java Fern and Anubias are good plant options that will let them hide, and get food.

Tank conditions

Thai Micro Crabs live in rivers and are used to moderate water flow. They use the water flow to filter food. Creating some water flow with a sponge filter will help move the water around letting them filter more food particles from the water.

Tank Maintenance

a thai micro crab crawling across the substrate of their aquarium

Regular water changes should be performed in their tank. Thai Micro Crabs are small and delicate and water change or cleaning their tank should be carried out carefully.

A net should never be used to clean their tank because it could seriously injure the Crabs if they get caught inside the net.

Best Tank Mates for Thai Micro Crabs

Thai Micro Crabs get along with their own species and should always be kept in a colony of 5 or 6. Keeping them in a colony helps them feel safe and secure. If kept in a larger aquarium then more can be kept together. 

Because they are defenseless and small, only non-aggressive tank mates should be kept with them. 

Best Tank Mates are:

Avoid keeping them with larger aggressive fish species like Cichlids, Goldfish, Angelfish and larger Catfish. Thai Micro Crabs shouldn’t be kept with other crabs because other crabs will eat them.

Health Issues

Shell Disease and Appendage Loss.

Shell Disease

Shell disease is an infectious and contagious condition that can be caused by a variety of different stressors, including poor water conditions, low dissolved oxygen levels, and inadequate nutrition. It occurs when opportunistic bacterial or fungal pathogens take advantage of weakened immunity in the fish and begin to invade their shells and scales. The lesions created by the infection can be visible to the naked eye, as white or yellowish patches, or they may be hidden beneath the surface. Left untreated, shell disease can be fatal to fish. It’s fatal because it prevents them from being able to breathe or digest food.

Appendage Loss

Appendage Loss is a serious condition that can lead to the loss of fins, tail, or other appendages. This condition can be caused by a variety of factors including infections, parasites, and bad water chemistry. It’s important to identify the symptom and diagnose the cause in order to effectively treat this condition before it leads to more serious issues.

By taking the time to inspect your fish regularly and create a healthy environment for them, you can help keep your fish healthy.

Feeding Thai Micro Crabs

Thai Micro Crabs are omnivore scavengers and mostly eat dead matter. They don’t hunt and will usually eat whatever leftover food or algae they find in their tank.

Thai Micro Crabs use the bristles on their body to filter food like microorganisms from the water. They eat these organisms when they clean themselves.

If they are housed with Dwarf shrimp, you can feed them the same food. The only concern is that dwarf shrimp may outcompete the Thai Micro Crabs because these crabs are slower and timid.

They can be fed pellets, flakes, wafers and sinking crab food. For fully matured aquariums there might not be a need to feed Thai Micro Crabs because of the abundance of free floating food. The algae and dead matter available in the tank should be enough to feed your crabs.

Related Questions:

Do Thai Micro Crabs Molt a Lot?

Thai Micro Crabs are small and have slow growth rate. They don’t molt as often as other crab species. When they do molt, the process is the same as other crab species.

Thai Micro Crabs will be under a lot of stress when they molt. Their tank shouldn’t be cleaned or rearranged when they are molting.

Can You Breed Thai Micro Crabs in Captivity?

Thai Micro Crabs are difficult to breed in captivity. They are relatively newly discovered species of freshwater crabs and there has not been a lot of research on them yet. Aquarium hobbyists who have tried breeding them have not been successful at keeping their offspring alive for long.

One speculation is that there is a nutrient that is found in their natural environment which may not be present in captivity. It’s not recommended to try breeding Thai Micro Crabs in captivity.

Author Profile
A woman with curly hair holding a cat.
Contributing Author & Social Media Expert

Maryna is an animal expert that has had dozens of animals in her life over the years. She has never found an animal that she didn't love immediately. It seems like every year she finds kittens that have been abandoned by their mom and she nurses them to health and finds homes for them. She contributes her vast knowledge about animals and family pets to our website and we're forever grateful to have her working with us. She's also an amazing graphics designer and has designed all of the social media images that we use across all platforms.