Thai Micro Crab: Care, Tank Mates, Breeding and More!

Limnopilos naiyanetri
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: April 13, 2024
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If you’re searching for a distinctive organism to add into your nano tank, the inclusion of Thai Micro Crabs could be a perfect decision. Recently introduced into the aquaculture hobby, these crabs bring a rare and exotic flair to any aquascape setting. With the help of practical experience and existing species literature, a comprehensive starter’s guide has been curated detailing their maintenance, ideal water conditions, compatible tank mates, breeding, and more. Continue reading to broaden your knowledge.

Article Summary

  • Thai Micro Crabs are a unique and exotic addition to nano tanks, known for their small size and spidery legs.
  • Thai Micro Crabs have a peaceful temperament and are suitable tank mates for small fish like Otocinclus catfish, dwarf shrimp, cherry shrimp, nerite snails, and mystery snails.
  • Breeding Thai Micro Crabs in captivity poses challenges, and the majority available in stores are wild-caught, contributing to limited available information about their reproduction.

Species Overview

Common namesThai micro spider crab, false spider crab, thai micro crabs, laos micro spider crab, pill box crab
Scientific nameLimnopilos naiyanetri
SpeciesL. naiyanetri
Size.4 in
Lifespan1.5 yrs
Minimum tank size2 gallons
Place in the tankMiddle
Care LevelEasy
Breeding Difficult

History and Background

First introduced to the aquarium trade in 2008 these crabs have charmed the hobby with their rounded bodies and big personalities. Though they might not seem much different from other species they can add many hours of entertainment to your aquarium with their high activity levels.

What is a Thai micro crab?

The Thai micro spider crab, or false spider crabs, is found in Thailand in only one river and is one of the few fully aquatic crabs. This crab species is gaining popularity in the aquarium hobby and isn’t commonly found in pet stores due to their tiny natural habitat range.


Originally these crabs were in the genus Hymenicoides but were moved to the Limnopilos genus in 1991 achieving their name Limnopilos naiyanetri.

Where did the Thai micro crab come from?

These tiny crabs originated from the Tha chin river in Thailand.

What are they called Thai micro crab?

They are called Thai micro spider crabs because of their tiny size and long spidery legs.


Close-up Image Of A Thai Micro Crab
(1) Close-up Image Of A Thai Micro Crab

While they initially don’t look like much the closer you get to these crabs the more in love you’ll fall with their quirky almost transparent appearance.

What do Thai micro crab look like?

These micro crabs have small rounded bodys that have silver, brown, or grey coloring. Their legs are beige and have tiny hairs lining them which helps capture food particles in the water column.

How big does a Thai micro crab get?

As an adult this micro crab species will have a body size measuring up to .4 inches, but their long spidery legs are actually only 1 cm long. In fact, false spider crabs are the smallest known freshwater crab making it extremely popular in nano tanks.

How fast do Thai micro crab grow?

Like many other crab species, thai micro crabs will reach their adult size in roughly 6 months. This is a fairly slow growth rate compared to other crab species and takes up to a third of their life.


Because of their slow growth, thai micro crabs don’t undergo the molting process as often as other crab species.

Temperament and Tankmates

Fish tank with aquarium plants and small species of fish
A Fish Tank With Small Fish Species

The process of choosing tank mates is extremely important to their well being because thai micro crabs are small and defenseless.

Thai crab behavior

These crabs are normally easygoing and peaceful companions for others in your tank. They are relatively active and you’ll likely see them scurrying across the bottom of the tank in search of food. They are fairly skittish and need ample hiding places to get away from any unusual activity such as people walking close to the tank.

Can Thai micro crabs live with fish?

Yes, thai micro crabs can live with small fish. Aggressive fish will not make good tank mates for this species.

What fish can live with thai micro crab? 

Otocinclus catfish are small fish that have been known to peacefully coexist with Thai micro crabs.

Compatible Tank mates

  1. Dwarf shrimp-a small shrimp that will not bother your crabs. Dwarf shrimp have similar living requirements and will let your crabs adapt to their presence without stressing them out.
  2. Cherry shrimp-a popular choice for small aquariums cherry shrimp will do well with thai micro crabs
  3. The Mystery snailtheir calm demeanor and protective shell will mean that your crabs will leave them alone. As an added bonus they come in a wide spectrum of colors that can brighten your tank.
  4. Thai micro crabs-When choosing tank mates you should also consider a species specific tank. Thai micro crabs do best when kept in a group of 4 to 5 crabs.
  5. Nerite snail-another peaceful snail species that will easily get along with your thai micro crabs.


Because of thai micro crabs’ method of sifting through the water for food there is some risk that they will consume tiny baby shrimplets. Adult shrimps will not cause any issue but if you are trying to reproduce shrimp do not keep them in the same tank.

Tank mates to avoid

  1. Other crabs– such as freshwater pom-pom, fiddler, red claw, and vampire crabs, should not be placed with Thai micro crabs because the latter are defenseless. It is strongly suggested to keep them separate.
  2. Large fish-other fish that might show aggression or mistake your thai micro crabs as a snack should be avoided at all costs.
  3. Crayfish-another crustacean that you should avoid due to their large size and aggression.
  4. Cichlids-though we mentioned you should avoid large fish earlier, you should at all costs avoid cichlids as they are particularly aggressive.
  5. Oscars-a large freshwater fish, oscars won’t have a second thought about eating your crabs.

Tank Requirements

Nano Aquarium
A Beautiful Nano Aquarium

While initial water conditions don’t seem that different from normal freshwater tanks it is extremely important that these micro crabs have stable living conditions and will not do well with change due to their sensitive nature.

Water Parameters

Tank Size2 gallons
Water TypeFreshwater
Water temperature72-82
Water pH6.5-8.0 (as close to neutral pH balance as possible)
Water hardness6-15 dKH

What type of water do Thai micro crabs need?

These crabs live only in freshwater and should be kept in aquariums that have 0 parts per million salinity.

Tank setup:

When planning and designing your initial tank set up be sure to include plenty of hiding places for your crab using driftwood, caves, plants, and other aquarium decor.

What kind of substrate to use

We recommend choosing a fine sand for substrate as it will allow you to add many live plants to the aquarium replicating the natural habitats of these micro crabs.

Do I really need a Filter:

Keeping pristine water parameters is very important as these small crabs will have a particularly hard time adjusting to any changes in water quality. As such you should invest in an excellent filtration system such as porous sponge filters or a canister filter to keep your aquarium life as happy as possible.

Do I have to have a Pump:

Having a pump is not necessary for this species as long as you have a good external filtration system. The small tank size and an external filter will provide enough circulation for your thai micro crabs and other aquatic animals without forcefully pushing them around the tank.

Should I add a Water heater:

You will likely need a water heater for your crabs as they are used to living in a tropical environment with water temperatures ranging between 72 and 82 degrees Fahrenheit.

What kind of Lighting is necessary

This species is not very specific when it comes to lighting preferences. However, we recommend a heavily planted freshwater aquarium to replicate their natural environment. Therefore you should cater lighting needs to the vegetation present.

Can I add Plants:

The addition of plants to your tanks can make your crabs feel right at home in their natural environment. While you can try to source plants that are native to the specific river they hail from, you can also choose to create a dense vegetation layer using more commonly found plants such as java moss, anubias, or other floating plants.


Adding vegetation will also provide hiding places for your thai micro crabs to play in as well as giving them a sense of safety.

Do Thai micro crab need land?

No, unlike other crabs these micro crabs are fully aquatic and do not require any terrain in their habitat. However, if you have other crab species in your aquarium you might have to cater to their needs.

How many gallons does a Thai micro crab need?

Since thai micro crabs grow less than .5 inches they do best in nano tanks ranging from 2-5 gallons.

Do Thai micro crabs need a heater?

Yes, these crabs have small bodies and are not able to cope with temperature changes. You should invest in a water heater that will keep the temperature in a very accurate and small range.

Diet and Health

Fish Food
Variety of Fish Food Inside A Container

Like other crabs, thai micro crabs are scavengers and will eat almost anything they can get in their mouths. However, you shouldn’t let them eat anything but the high quality diet you have designed for them, read on below to get a snapshot of what they eat and why.

What do Thai micro crab eat

Thai micro crabs filter feed and are able to use the bristle hair along their leg span and body to filter water and pass any particles up to their mouths. They are defined as omnivores and will eat both meat and vegetable matter. In their natural environment these crabs graze on plant matter, decaying organic matter, and other small particles of food.

What to feed Thai micro crab?

Algae wafers, shrimp food, and other sinking pellets will allow your Thai micro crabs to graze for food particles that other tank mates don’t want. Additionally, having thick vegetation in your tank will provide a surface for algae to grow on giving them another food option.

How to feed Thai micro crab?

To feed your thai micro crabs drop sinking pellets and allow them to dissolve. As your thai miro crabs crawl along the bottom of the tank they will scavenge for food and eat what they want. While this feeding method is easy you will have to closely watch tank conditions as water parameters will quickly change in small tanks.

How often to feed Thai micro crab?

If you are just starting your freshwater tank you should provide your crabs with food once a day. For more mature aquariums you can likely feed your crabs every other day as they will be able to graze on food particles and other organic matter in the tank.

How much to feed Thai micro crab?

Drop two to three sinking pellets in your tank for each of your thai micro crabs.

Common diseases of Thai micro crab?

There aren’t any species specific diseases that are known to this crab, however it is worth pointing out that they are extremely sensitive to ammonia and nitrates. Like other aquatic life you should keep your tank environment in pristine condition to avoid any ailments.

How long do Thai micro crab live?

In ideal living conditions thai micro crabs will live to be roughly 1.5 years old.


Thai Micro Crab Climbing On An Aquarium Plant
(2) Thai Micro Crab Climbing On An Aquarium Plant

Due to their recent introduction to the aquarium trade not much is known about breeding thai micro crabs in captivity and aquarists have reported limited success. A majority of those sold in stores are wild caught and aquarists who want them should look at sustainably sourcing them from a company or store.

Can you breed a Thai micro crab?

Currently, efforts to breed the freshwater spider crab in captivity have not been successful. While this species is fairly new to the trade so there isn’t much information regarding their reproduction, not many people try to breed them as they are fairly plentiful in their native environment.

How to breed a Thai micro crab?

What is known about breeding thai micro crabs is that the female thai micro crabs usually hold the eggs under her pleon.

The eggs begin as orange, then gradually turn yellow, and eventually grey. Compared to the size of thai micro crabs their eggs are quite large ranging from .01-.02 inches (4% of their adult body size). The female will house these large eggs in their bodies for several weeks before laying roughly 70 eggs. Unlike either crabs, the reproductive process happens entirely in freshwater.

Thai micro crab FAQS

Read below to find the most common questions associated with thai micro crabs and their care. 

Are Thai micro crabs fully aquatic?

Yes, unlike other crabs these micro crabs never need to step foot on land and have evolved to be totally aquatic.

Are Micro Crabs Aggressive?

No, thai micro crabs are generally non aggressive and make good tank mates for non aggressive fish.

Is the Thai micro crab for you?

If you’re looking for a personable addition to a nano tank or paludarium, the thai micro crab can be an excellent choice.


In conclusion, thai micro crabs are an excellent addition for any aquarist looking to add something exotic and unique to their micro tank.

Featured Image –

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