The Chinese mitten crabs (Eriocheir sinensis) are aggressive, burrowing crustaceans. Although these crabs can be interesting augmentations to certain freshwater aquariums, generally, they have been exploited extensively as a food resource since the 1990s.
The Chinese mitten crabs are large freshwater crabs that can be found in a wide range of habitats and water conditions. Their hardy nature, adaptability, and ease of feeding make them excellent invaders.
If you are thinking of keeping the Chinese mitten crab as a pet, or simply want to learn more about this species, you have come to the right place.
In this guide, I gathered everything that is currently known about Eriocheir sinensis including ideal tank setups and how to care for them.
| Important: Eriocheir sinensis (еhe Chinese mitten crabs) is a very successful invasive crab species in Europe. This species has been nominated as among 100 of the “World’s Worst” invaders.
Even if it is not banned in your state or country, NEVER release them into the wild! These crabs can alter ecosystems, causing the loss of native species, and having major economic consequences. |
Quick Notes about the Chinese Mitten Crab
| Name | Chinese mitten crab |
| Other Names |
Chinese freshwater edible crab, Shanghai crab, and Chinese river crab |
| Scientific Name | Eriocheir sinensis |
| Tank size (minimum) | 15 gallons (~60 liters) |
| Type | Freshwater |
| Keeping | Easy |
| Breeding | Very difficult |
| Average size (carapace) | 3 – 3.5 inches (7 – 8 cm) |
| Average size across the leg span |
7 – 8 inches (about 18 – 20 cm) |
| Optimal Temperature | 60 – 70°F (15 – 21°C) |
| Diet | Mostly herbivore/omnivore |
| Temperament | Aggressive |
| Life span | up to 5 years |
| Color Form | Brown |
Distribution of the Chinese Mitten Crab
The Chinese mitten crab is a native of East Asia. Its native range extends from Hong Kong to the border with North Korea.
In 1912, these crabs were introduced into Germany. Since then, they have spread subsequently throughout northern Europe. Nowadays, the Chinese mitten crabs estimated distribution ranges from Finland, through Sweden, Russia, Poland, Germany, the
Czech Republic, Netherlands, Belgium, and England to France.
These crabs are also found in San Francisco Bay, Chesapeake Bay, and the mid-Atlantic coast of North America. So, this species has become one of the most notorious aquatic invaders in these areas.
Habitat of the Chinese Mitten Crab
The Chinese mitten crabs inhabit rivers, streams, creeks, marshes, lakes, as well as estuaries, and intertidal areas from lower shorelines to about 10 m in depth.
This species does not have a preference and can be found in rocky, muddy, and vegetated areas.
The Chinese mitten crabs live as an adult predominantly in freshwater but migrate seawards to breed.
Description of the Chinese Mitten Crab
The Chinese mitten crabs can grow pretty big. On average, the carapace of an adult crab can grow to about 3 – 3.5 inches (7 – 8 cm) long, with a leg span up to 7 – 8 inches (about 18 – 20 cm) or even more. The total weight of the adult individuals can reach 0.5 – 0.6 lbs (or 250 – 300 grams)!
Therefore, it will be better to give them extra space in your tank in case they grow a little larger than expected.
The crabs’ coloration varies from a brownish-orange (mostly among juvenile crabs), to a more greenish-brown in adult crabs and in newly molted crabs.
Distinguishing characteristics include:
- The dense patches of setae, or hair, on the white-tipped chelae (claws). Actually, that gives this crab its name because hairy white-tipped claws resemble mittens.
- 4 lateral spines on either side of its eyes.
- A distinctive notch located between its eyes.
- The carapace is slightly wider than long.
Note: It is well-known fact that the mitten crab is a traditional and common savory food in China due to its delicious taste and high nutritional value.
Lifespan of the Chinese Mitten Crab
The lifespan of this species depends on maturity and breeding because these crabs die soon after that.
So, the normal lifespan of female and male the Chinese mitten crabs varies from 1-3 years in China to 3-5 years in Europe.
Typical Behavior of the Chinese Mitten Crab
Although this is a fully aquatic species, the Chinese mitten crabs are also capable of crossing dry land to enter new river systems.
Field observations of mitten crabs revealed that these crabs are extremely active during the day and far less active during the night.
These crabs are classified as burrowers. In nature, they can cause serious river bank erosion. However, it is the smaller juveniles (up to 1 inch carapace length or 2.5 – 3 cm) that mostly construct and inhabit these burrows (up to 20 inches deep or 50 cm).
Chinese mitten crabs are aggressive and territorial animals. Males exhibit a significantly higher rate of aggression than females. However, their aggressive activity can decline with the increasing availability of both shelter and food.
Features:
- Social: No
- Active: Yes
- Peaceful: No
- Territorial: Yes
- Burrowers: Yes
Diet of the Chinese Mitten Crab
Chinese mitten crabs are predominantly omnivorous and detritivorous feeders. Basically, it means that they will eat whatever they can get.
Analysis of their gut content showed that they feed on aquatic plants, algae, detritus, fish eggs, insects, and small invertebrates.
However, their feeding habits shift a little bit throughout the life cycle. For example, the Chinese mitten crab becomes more carnivorous as it ages.
If these crabs are kept as pets in aquariums, suggested foods include (some links to Amazon):
- Vegetables (like broccoli, cabbages, carrots, cucumbers, lettuce, corn, spinach, peas, squash, leafy greens, etc.).
- Fruits (Apple (only sweet), banana, pearl, melon, mango, etc.).
- Leaves.
- Shrimp pellets.
- Shrimp Granules.
- Fish food (TetraMin® flakes, etc.)
- Shrimp food (Hikari’s crustacean food like Hikari Shrimp Cuisine, Algae wafers, etc.)
- Frozen blood worms.
- Detritus worms.
Features:
- Diet Type: Mostly herbivorous /omnivore
- Food Preference: Mix of meats and vegetation.
- Feeding Frequency: 3 – 4 times a week for adults. Daily for juveniles.
Related article:
How often should We Change the Food?
Crabs are slow eaters. Therefore, you can leave their food for 24 hours before removing it to prevent moles.
How Often to Feed Chinese Mitten Crabs?
Adult crabs should be fed 3 – 4 times a week. DO NOT let them starve or they can start cannibalizing very fast.
Do Chinese Mitten Crabs Need Calcium?
Yes, they do. Even more, calcium is a crucial component of a crab’s exoskeleton and overall health.
Calcium can be found in:
- kale,
- broccoli,
- spinach,
- cuttlebones,
- eggshells (dusted),
- figs,
- nuts,
- wonder shells,
- oyster shells,
- seaweed,
- seeds,
- insects, etc.
It is highly recommended to keep a small piece of cuttlefish bone (link to Amazon) in their enclosure all the time.
| I highly recommend reading my article “How to Supplement Shrimp and Snails with Calcium”. |
Are Chinese Mitten Crabs Plant Safe?
No, they are not plant safe. Chinese mitten crabs are large, strong, and voracious eaters. They will eat, cut, shred or uproot plants in the tank.
It is not recommended to keep them in planted tanks. The only viable options for this species are:
- plastic plants,
- floating plants,
- some cheap plants that you are ready to lose.
Related articles:
Keeping and Housing the Chinese Mitten
Chinese mitten crabs are very adaptable animals and can thrive in most situations. Therefore, care is quite simple and straightforward.
Nonetheless, if you want to make them happy, you still need to address their core needs. Here are some care guidelines to help you out.
Tank Size:
Make sure to keep the Chinese mitten crab in large tank setups because of its growth potential. In addition, this species is very active and requires a lot of space to move in the tank.
Hence, a 15 gallon (~60 liters) is the minimum recommended tank size.
As adults, one male and one female may be kept together in the same enclosure of 40 gallons (180 liters) or more, but two adult males would need far more space to reduce territorial fighting.
Important:
- Having a smaller tank will significantly limit their freedom. It will also make them more aggressive towards each other. Eventually, it will stress them and reduce their lifespan.
- Chinese mitten crabs are very good escape artists. Your tanks should be covered. However, they are also pretty strong and can move light lids, so keep that in mind.
Water Parameters:
If you are a first-time crab owner it is important that you cycle your tank before bringing any pet home. Once the tank is cycled you need to check the quality of the water using a test kit.
Temperature: Their preferred water temperature is between 60 – 70°F (15 – 21°C). This temperature range is considered optimal for the Chinese mitten crabs.
Nonetheless, Eriocheir sinensis exhibits a wide range of temperature tolerances. Their growth ceases only at temperatures below 45°F (7°C) and above 86°F (30°C).
pH: Ideally, pH should be provided for this species in the range of 7.0 – 8.5.
Hardness: They will appreciate optimal KH 3 – 20 and GH between 3 – 25 GH.
Salinity: Adult Chinese mitten crabs are extremely euryhaline. It means that they can quickly adapt from highly saline to low brackish and freshwater environments
Interesting fact: Adult Chinese mitten crabs also are highly tolerant of desiccation and are able to remain unsubmerged for several
hours without mortality.
Filtration:
Having sponge filters in the aquarium with Chinese mitten crabs will be just a very bad idea. The point is that these crabs will definitely chip, chew and break apart the sponge.
Therefore, you need to have filtration that cannot be easily damaged, for example, hang on the back or canister filters.
Lighting:
No special requirements. Basically, you can choose whatever you like.
Substrate:
In the aquarium, Chinese mitten crabs should be provided with small gravel and/or sand substrates. It will be an ideal setup for them.
Decorations and Hiding Spots:
Chinese mitten crabs will appreciate all types of leaves, rocks, wood, plants, PVC pipes, and other decorations to enrich the environment in your tank.
The presence of shelter has a significant effect on reducing the rate of initiation of aggressive behaviors by Chinese mitten crabs.
It is also very important to minimize stress to your crabs by giving them a lot of places to hide. This is also critical for the molting process!
Related article:
Chinese Mitten Crab and Molting Cycle
The molting process (the molt cycle) is the process by which a crab grows. Because crabs have an exoskeleton, they must molt (shed the old exoskeleton) in order to grow. It also allows them to restore lost limbs.
This process consists of 4 phases:
- pre-molt,
- molt,
- post-molt.
- inter-molt.
For more information, read my article “Crabs and Molting Process”.
Important:
- NEVER disturb your crabs when they are about to molt. Do not panic even if you have not seen your crabs for a few days in a row! Give it time. This is the most stressful moment in its life.
- Keep putting and replacing food in the tank! You never know when they can come up from the molt.
- Keep giving them calcium-rich food.
- Also, do not remove the old exoskeleton from the tank. It contains lots of minerals and your crabs will eat it later.
Rules: How to Care and Handle Chinese Mitten Crab:
- Chinese mitten crabs are not pets you can play with. Do not take them out just because you want to.
- Chinese mitten crabs should never be lifted up by their legs or claws! They can lose a limb by autotomy.
- Do not leave uneaten food for too long. It can cause smell and bacteria in their enclosure. Remember, these crabs like to store uneaten food in their burrows.
- Provide as many hiding places as you can.
- Make sure the lid of the tank is closed tightly so that they cannot escape it.
Related article:
Chinese Mitten Crab – Male and Female Differences
Chinese mitten is sexually dimorphic. There are a few indicators that give away the gender of the animal.
- Size. Females are generally smaller than males.
- Setae: Although males and females both exhibit hairy chelae, the setae are generally fuller and cover a wider area of the chelae in the males.
- Abdomens. After reaching a size exceeding approximately 1 inch (or 2.5 cm) in carapace width, the male and female crabs can be differentiated by the shape of the abdomen. Males have a narrow and slimmer plate (triangular) while females have a broad plate on their belly.
Breeding the Chinese Mitten Crabs
The Chinese mitten crabs have a catadromous life cycle, including the adult stage which is spent in freshwater, reproduction in brackish water, and a marine larval stage.
These crabs reach maturity at approximately 1.5 inches (3.5 cm) in carapace width.
Interesting fact: Generally, this species reproduces only once or rarely twice and then both male and female crabs die. The males die after mating and the females die after the eggs hatch.
The age at which Chinese mitten crabs reach sexual maturity varies from 1-3 years in China to 3-5
years in Europe.
Eggs:
After mating in the brackish water of estuaries females move toward higher salinities and release their larvae in early spring.
According to the study, Chinese Mitten crabs are capable of spawning up to 2 times from a single
mating.
Females can have from 250,000 to 1,000,000 eggs for the first spawn. Second maturation occurs about a month after the first spawn, which is much shorter than the first maturation (3–4 months).
They carry eggs attached to the pleopods (abdominal appendages) on the underside of their abdomen.
Hatching:
It takes 3 weeks for the fertilized eggs to develop into zoeal larvae at temperatures of 60 – 70°F (15 – 21°C) and a suitable salinity (20–25 %).
Before hatching, the eggs turn greyish, it is also possible to see developed eye spots. These are indicators of imminent hatching.
Larvae:
Larval development includes 5 zoeal stages and one megalopa stage.
Depending on the temperature, food availability and salinity, larval development can range from 2–4 days
for each of the zoeal stages and from 5 to 10 days for the megalopa stage.
It is recommended to start doing water changes after the first 3 days of culture. At first, it should be 10–20% (during the 2nd and 3rd stage), 40–50% (during the 4th and 5th stage), and 100% at the end of the rearing
cycle.
According to the study, Mitten crab larvae are able to develop from hatching through a metamorphosis at temperatures ranging from 53 – 65°F (12 – 18°C)and at salinities from 15 to 32%.
Even under optimal conditions, the survival rate is usually about 10–15% from the first stage to megalopa. Nonetheless, considering the number of larvae it can be seen as a good result.
Mitten crab larvae diet includes primarily microalgae, phytoplankton, rotifers, copepods, and artemia.
Cannibalism often accounts at metamorphosis from stage 5 to megalopa. However, it can be reduced by increasing feeding ration and optimizing the feeding regime.
In nature, the megalopa settles in brackish water in late spring and move upstream along with the tidal currents at a speed of 8–12 km per day.
After 7–10 days, the megalopa transforms into juveniles which migrate continuously upstream (1–3 km per day) into freshwater.
Interesting fact: During the upstream migration, Juvenile Chinese mitten crabs can reach rivers, lakes, and ponds as far as 1200 km from the coast while growing to adult size.
Chinese Mitten Crabs and Suitable Tankmates
This is an aggressive and territorial species. These crabs are not social. It can be risky to house multiple animals in the same tank as well, especially males.
Chinese mitten crabs should not be kept with crabs, crayfishes, dwarf frogs, and especially freshwater snails. They are voracious consumers of freshwater gastropods.
Chinese mitten crabs usually do not hunt for fish. Nonetheless, in aquariums, bottom-dwelling, slow-moving, or fish with long fins (like Betta) should be avoided as well.
The probability of these relatively slow crabs capturing healthy, free-swimming fish is relatively low.
Dwarf shrimp are too small and too fast for them. However, they are opportunistic and will eat whatever they catch. It means that you may still lose shrimp from time to time
Therefore, ideally, these crabs are usually better in solitary confinement without tank mates.
In Conclusion
Chinese mitten crabs are very adaptable animals and can be easily kept in the home aquarium even by beginners.
The biggest concern is their aggressive nature, as they may attack other crabs, snails, etc.
In addition, if you decide to keep one, you should also remember that this is an invasive species – be very careful and never release them into the wild.
References:
- Anger, Klaus. “Effects of temperature and salinity on the larval development of the Chinese mitten crab Eriocheir sinensis(Decapoda: Grapsidae).” Marine ecology progress series. Oldendorf 72, no. 1 (1991): 103-110.
- Herborg, L-M., S. P. Rushton, A. S. Clare, and M. G. Bentley. “Spread of the Chinese mitten crab (Eriocheir sinensis H. Milne Edwards) in Continental Europe: analysis of a historical data set.” In Migrations and dispersal of marine organisms, pp. 21-28. Springer, Dordrecht, 2003.
- Sui, Liying, Mathieu Wille, Yongxu Cheng, Xugan Wu, and Patrick Sorgeloos. “Larviculture techniques of Chinese mitten crab Eriocheir sinensis.” Aquaculture 315, no. 1-2 (2011): 16-19.
- Rudnick, Deborah A., Kathleen M. Halat, and Vincent H. Resh. “Distribution, ecology and potential impacts of the Chinese mitten crab (Eriocheir sinensis) in San Francisco Bay.” (2000).