Freshwater Crabs

a Freshwater Crab crawling around on the sand

Are you considering getting a pet, but don’t want the same old cats and dogs? Freshwater Crabs may be the perfect pet for you! These small crustaceans are becoming increasingly popular as family pets.

Freshwater Crabs are members of the family Potamidae, which includes over 700 species of Freshwater Crabs found all over the world. They come in a variety of sizes , colors, and shapes. Some of the most popular species of Freshwater Crabs include the red claw crab, the fiddler crab, and the blue land crab.

There are a number of different types of crabs available in the United States, and they all have different sizes, shapes, colors, and activity levels. There is a type for every family.  These critters are ideal for kids, and parents will love that they only need to be fed once a day, and that they can clean up after themselves. While they may not be as popular as dogs and cats, freshwater crabs are just as fun and easy to take care of, and can provide years of enjoyment.

Freshwater Crabs are a great option for anyone who wants a pet that doesn’t need too much of their time. They can be fed once per day, and they will clean up after themselves. They are relatively inexpensive to purchase, and they are easy to care for. They are also a good introduction to the world of pet keeping for young children.

Families love them because they are relatively inexpensive, they are a great option for those who want to start out small. They are also easy to care for, requiring minimal attention. They are also a lot of fun to look at, and they don’t require much space. Because they’re so small they can be kept in an aquarium as small as 5 or 10 gallons.

What they lack in looks they make up for in personality.  Freshwater Crabs are active little creatures that will scuttle around the floor of your tank, looking for things to scavenge. This is usually food that others in the tank didn’t eat. A freshwater crab is just one of the many unique animals that make a great addition to your family’s aquarium. 

Freshwater Crabs are omnivores, meaning they will eat both plant and animal matter. They can be fed a variety of foods such as shrimp, fish, vegetables, and even commercial crab food. It is important to provide them with a balanced diet in order to keep them healthy.

Freshwater Crabs are social creatures and can be kept in groups. They are also very active and will often climb on rocks, explore their tank, and even dig tunnels. Watching them play is a great way to bond with your pet crab.

Freshwater Crabs are also relatively low maintenance pets. They require weekly water changes and occasional tank cleanings, but other than that they don’t need much attention. This makes them a great pet for busy people who don’t have a lot of time to devote to their pet.

Overall, Freshwater Crabs can make great family pets. They are easy to care for and provide hours of entertainment. If you’re looking for something different than the usual cats and dogs, then freshwater crabs may be the perfect pet for you!

Freshwater crabs Information

  • Average Length: 1 – 4 inches depending on species
  • Colors: Brown, Orange, Red, Gray and Blue
  • Attention Needs: Low
  • Tolerance to Heat and Cold: No
  • Good Pet: Yes!
  • Good with Other Crabs: Depends on the specific crab species
  • Good with Other fish species: Depends on the crab species
  • Good for Less Experienced Pet Owners: Yes
  • Health Concerns: Shell Disease and Appendage Loss. 

Average Life Span: 1 to 5 years

Physical Appearance of Freshwater Crabs

a Freshwater Crab holding on to some aquatic plants and trying to filter feed

Freshwater Crabs are crustaceans (invertebrate organisms with a thick exoskeleton) that have 10 legs. In terms of body structure they are closely related to lobsters, shrimp and crayfish. Like these creatures, Freshwater Crabs also don’t have a backbone or a bony skeleton. Instead they have a hard exoskeleton that supports their delicate body and protects them from predators. They shed this exoskeleton several times during their lifetime through a process called molting.

Freshwater Crabs have a flat, short and somewhat circular-shaped body. They have 5 rows of legs with their first row having claws. The claws are not used for movement but help them to burrow and catch prey. Some Fiddler Crab species like Fiddler Crabs have larger claws than other species.

The legs have multiple joints and are stiff. The way their legs are designed makes it hard for them to move forward or backwards with any speed. This is why Crabs usually only move sideways to get around.

There are over 9 different species of Freshwater Crabs that are commonly kept in aquariums. Even with the smaller selection, there still is a huge choice in colors, size and textures.

A few commonly kept Freshwater Crabs are:

Temperament of Freshwater Crabs

a Freshwater Crab crawling around on the sand outside of the water

Freshwater Crabs are nocturnal and mostly active during the night. They are scavengers who will look for leftover food and other organic waste inside their tank that can be eaten. They will climb on anything that they find which is why securing their tank lid is extremely important.

When introduced to a new tank they will likely spend most of their time in hiding. As they become used to their new home the Crabs will gradually come out of hiding. Some species like Pom Pom crabs don’t usually hide and are more active.

The temperament of Freshwater Crabs also varies depending upon the species. While most are peaceful some like the Red Claw Crabs tend to be extremely territorial and aggressive. Male Fiddler Crabs are also known to get aggressive with other male Fiddler Crabs over territory and females.

Best Habitat for Freshwater Crab

The Fiddler Crabs habitat needs depend on the individual species. While many are aquatic, some like Fiddler Crabs are semi-terrestrial. Fully aquatic crabs spend their entire life submerged in water and semi-terrestrial live both on land and water.
Find out about the needs of the Freshwater Crab species before you set up your aquarium.

Crabs can climb almost anything which makes them amazing at escaping. Keeping the top of the tank secured with a mesh top will make sure they don’t escape.

Tank size

a Freshwater Crab climbing up an aquatic plant

For a tank that is going to house only Freshwater Crabs, we recommend a tank that’s at least 5 gallons. If you plan to build a community fish tank and want to add a large number of Freshwater Crabs or fish then a larger tank will be needed.


The ideal water temperature for Crabs is between 72 and 82°F. Depending on the specific Crab species the temperature can vary slightly.

Water Hardness and PH

Depending on the species the pH should be between 6.5 to 8.5 and the water hardness between 4 to 16 dGH.


The lighting conditions of Freshwater Crabs will depend upon the type. Standard lighting conditions will do for most but some like Thai Micro Crabs prefer a darker environment. Having floating plants and lots of hiding places can help replicate the dark lighting conditions for Thai Micro Crabs.

Tank Substrate

For Freshwater Crabs a sand substrate is recommended. Sand allows the Crabs to burrow and hide. Using gravel is not recommended because it is hard and will prevent your Crabs from burrowing and hiding. Gravel can damage their legs and claws.

a Freshwater Crab crawling around on the sand outside of the water


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.

Before adding plants make sure to check the compatibility of your Crab type with plants. Some like the Red Clawed Crab are known to destroy living plants. Tanks that have Red Clawed Crabs should not have living plants, but plastic ones seem to be fine.

Tank conditions

Before introducing any Freshwater Crabs to a new tank, make sure to properly cycle the water as it will help promote the growth of beneficial bacteria.

A few Crab types like Fiddler Crabs need brackish water. Brackish water refers to water that has a higher salinity level than freshwater but less than seawater. To get the correct salinity level in your tank, you will need to add a teaspoon of marine salt for every gallon of water.

Tank Maintenance

The water temperature, pH and the level of dissolved organic compounds should be checked daily. Crabs cannot tolerate rapid changes in their tanks’ water conditions, maintaining consistent water conditions is important.

A 10 to 25 percent water change should be done every other week. The filter media should be cleaned once a month to ensure they work efficiently.

a Freshwater Crab on the bottom of their aquarium

Any new inhabitants should be introduced gradually to the tank. New inhabitants can feel stressed which can cause diseases that can affect existing aquatic organisms inside the tank, including your Freshwater Crabs.

Best Tank Mates for Freshwater Crab

The tank mates that you can keep will depend upon the type of Freshwater Crab and the water conditions the Crab needs. Most crabs need freshwater, but Fiddler Crabs need brackish water which most freshwater fish cannot live in. Refer to the specific Crab species you are thinking about getting to find the best fish to pair them with.

Avoid keeping Crabs with larger aggressive fish species like Cichlids, Goldfish, Angelfish and larger Catfish.

Many Freshwater Crabs are known to eat snails, it’s best to avoid adding snails to your tank.

Health Issues

an illustration of a lost appendage for a crab

A healthy Freshwater Crab will be active and have bright coloration on their exoskeleton. While crustaceans like Crabs are less prone to getting infected with diseases, some commonly found diseases are:

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.

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.

Feeding Freshwater Crab

a pile of colorful fish flakes

Freshwater Crabs are omnivores and should be fed a mixture of plant and animal-based food. In the wild they will generally graze feed all day, but in your aquarium you only need to feed them once a day. They generally feed on smaller crustaceans, insects, fish and plant matter. Some also occasionally eat algae.

In a captive environment they should be given freeze-dried, low-grain/no grain pellets or flakes. They can also eat frozen foods or live food like bloodworms and brine fish. Plant-based food like algae wafers, blanched peas and zucchini should also be given to them. As mentioned before, Freshwater Crabs love to snack on snails and they can occasionally be feed snails as well.

Feeding a well-balanced combination of plant and freeze-dried foods will keep your crab healthy. When giving them food, ensure that the food sinks to the bottom of the tank. By making sure it sinks, it will prevent the food from being eaten by fish in your tank. If you have a larger tank you can use a Shrimp Feeding tube. This will ensure the food reaches the bottom of the tank without being eaten by others in the tank.

If you use a feeding tube the crabs will know where their food is, and you will be able to see how much they are eating. You can feed them more or less, depending on how much food you see where the tube drops the food.

One more important thing to remember is to thaw any frozen food before giving it to them.

Most Crabs need calcium supplements. You can make sure they get enough by adding cuttlebone (a mineral bar typically used for birds) inside their tank. It’s best if you break it up into smaller pieces or even grind it up for them. You can also add calcium supplements directly to their food. The calcium supplement helps them with molting and also strengthens their exoskeleton. If you want them to have a healthy shell and be able to molt easily, make sure they have all the calcium they want. Adding a few pieces of ground egg shells should give them a good source of calcium.

Check the dietary needs of your Fiddler Crab species before feeding them.

Related Questions:

How do Freshwater Crabs Molt?

Molting is the process of shedding the exoskeleton and almost all crustaceans molt. Crabs molt by cracking open their shell from the back and come out in a soft shell covering. While molting the Crabs may sometimes lie still on their back. Many Crab owners can get concerned about this behavior but it is normal for them to do this when they are molting. If you find your Crabs lying on their back, make sure to check if they are molting before thinking they are sick.

Crabs generally burrow or hide when they are going to molt. They are most vulnerable during their molting period. After molting it takes some time for them to grow back their hard exoskeleton and they can be an easy target for predators before it grows in.

My Crab has Missing Legs and Claws, What Should I do?

There is no need to worry because the Crabs are capable of regenerating their missing claws and legs when they molt. If you have purchased a Crab with a missing leg or claw, wait for a few molting periods. The claws or missing legs should grow back fully after they molt a few times. To help them you can add iodine supplements to your tank as it will help them with molting.

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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.