10+ Fun Facts About Fiddler Crabs As Pets

This article will explain 10+ fun facts about fiddler crabs as pets and a care sheet you could possibly need to know about keeping fiddler crabs, including their unique behaviors, tank setups, and much more.

Let’s get started and find out some interesting information about these intriguing crustaceans!

For people, it is getting more and more common to add creatures other than fish into their aquariums.

Some people are moving toward plants creating a paludarium, while others move toward invertebrates.

Fiddler crabs are one of the most popular invertebrates you can buy.

They are easy to care for, which makes them great for those keeping crabs for the first time. They won’t take up much space either because of their small size.

Their claws demand your attention. Males have one larger claw which sets them apart from other species. This unique look creates a different attraction for your tank.

Care Level:Easy
Color Form:Various, but most are brown/orange
Lifespan:2-3 years
Size:1-2 inches
Fiddler Crab Diet:Omnivore
Minimum Tank Size:10 gallons
Tank Set-Up:Shallow water with areas above the surface
Compatibility:Species only tank or carefully selected community
Fiddler Crab PhylumArthropod


Fiddler Crab Species, Genus, and Fiddler Crab Scientific Name

Crab Names: Fiddler crabs, sometimes known as calling crabs, are a large group of crustaceans that make up the Ocypodidae family along with ghost crabs

There are roughly 100 closely related species belonging to the genus Uca biology (Fiddler Crabs). This article will cover how to care for all types of fiddler crabs.

This entire group of Fiddler Crabs is composed of tiny crabs – the largest is slightly over two inches (5 cm) across.

Where Do Crabs Live: Fastest Way To Sand Crabs

They are found throughout the world, ranging across both sides of the Atlantic, the Eastern Pacific, and the Indo-Pacific.

In these areas, they enjoy mangroves, salt marshes, and sandy/muddy beaches. These are coastal habitats with brackish water.

Fiddler Crab Lifespan

Unfortunately, many pet crabs stores advertise them as freshwater fiddler crabs species, but keeping them in freshwater hurts their health and reduces their life span. 

In the right conditions, they can live for 2-3 years. They are easy to care for and will even survive some basic mistakes.

If you have only kept fish before, then there are a few things you’ll have to get used to, such as their regular molting. There are lots of more important differences which we’ll cover throughout this article.

Typical Behavior

An important skill for living on the coast is the ability to survive both in and out of water. These crabs are semi-terrestrial meaning that their time is split between sitting on land and being submerged in water.

They have both gills and primitive lungs, which lets them breathe whilst in water and air.

Another interesting behavior you will notice is their claws. This could be used for courting females, digging burrows as shelter, or fighting with other males over territory.

Individuals can often be seen raising and lowering their claws as if they’re waving, this is their way of communicating with each other. The signal they give changes depending on how far away the target is.

They’re generally peaceful creatures; competing males are the only time aggression is shown.

Every eight weeks they will molt, leaving their old exoskeleton. If they have lost a limb, a new one will have developed by the time they molt.

10+ facts about fiddler crabs

  1. Fiddler crabs are highly specific eyes
  2. The males have one larger claw.
  3. The bigger claw could be as much as twice the size of the body
  4. Fiddler crabs are fantastic builders
  5. Fiddler crabs are great swimmers
  6. They employ their claws of a smaller size for feeding
  7. The Fiddler crab is a small crustacean
  8. Fiddler crabs are all omnivores
  9. Fiddler crabs can live for a period of two years or more
  10. Fiddler crabs are able to communicate by drumming and waving
  11. They possess an acute sense of smell
  12. Fiddler crabs play a significant part in the coastal ecosystems
  13. They undergo molting to develop
  14. The different species of fiddler crabs are colored differently
  15. Fiddler crabs are a species with a social hierarchy


The first thing that stands out when you see fiddler crabs are their claws. Male crabs have one major claw. The major claw is much bigger and gets prioritized as a tool. They also have one minor claw. Female crabs have two minor claws.

Behind their claws are four more pairs of legs used for walking.

The whole crab is covered in a hard coating to protect it from attackers. The main body is protected by a carapace (a hard plate that protects the organs).

At the front of the body are two stalked eyes, a pair of antennae, and a rostrum. The antennae are used to gather information about their surroundings.

Most of the species you can buy are quite small, rarely having a body larger than 1-2 inches.

Color Changing Crab

The color will vary depending on the stock you find, but they are generally not as colorful as fish. Most are some shade of brown or orange all over, but you may find some with more distinctive coloring and features.

The Uca perplexa, for example, has a bright yellow major claw that stands out against the rest of its brown body.

Male vs Female Crab

It’s easy to tell males and females apart. Females are smaller and have two small claws, only males have the major claw.

Fiddler Crabs Habitat

Fiddlers Crab House: Where Do Fiddler Crabs Live?

These crabs normally live on the coastline, a habitat that is known for its changing conditions.

The change in tide and their natural movement means that some of their time will be spent underwater and other times they’ll be on land.

Their surroundings would include a sandy substrate and a variety of rocks to hide in between. Plants are also sometimes present.

The brackish water would be warm, slightly alkaline, and well aerated by water movement and waves.

Fiddler Crabs As Pets: Tank Setup

Fun Facts About Fiddler Crabs As Pets
Fiddler Crabs As Pets

Setting up a tank for fiddler crabs is simple, but it’s not the same as setting up a fish tank.

You should start with a layer of soft, sandy substrate along the bottom of the aquarium. Sand is important because they need to be able to sift through it to feed and burrow. 

The sand should slope up to a raised area of the tank which sits above the surface of the water; this gives the aquarium crabs access to land.

Use rocks to give them somewhere to hide away. Live plants will probably be destroyed so are best avoided.

Don’t fill the tank all the way to the top with water, since air is just as important. You should fill it about a fifth of the way up with water, then your sandy slope can lead to an area above the surface.

The brackish water has low salinity, but you still can’t use freshwater. Keep salinity between 1.01 and 1.08.

Use a heater to keep the temperature between 75-86°F. The pH should be 8.0-8.3 and the hardness around 15 KH.

As they are naturally used to high oxygen levels, you need to aerate the tank. You can use either an air pump or a strong filter outlet.

What Size Aquarium Do They Need?

Fiddler crabs need at least a 10-gallon aquarium (this can comfortably fit 1-4). Give each additional crab 3-5 gallons. If they are too cramped, the water conditions will get worse and it may cause disease.

Fiddler Crab Tank Mates

You can add some fish in with them to make a community tank, but your options are limited. 

Most freshwater fish won’t survive in brackish waters, and usually, they will either be attacked by the crabs or larger fish will attack the crabs.

Some people have had success with Mollies because they can thrive in low-salinity environments but they may be too big unless you choose to use a larger tank of 30 gallons. 

Some other options include Platies, Swordtails, Guppies, and Bumblebee Gobies.

Any fish included in your aquarium requires to be fast enough to get away from the rare attack of a claw. It is safest to keep crabs on their own if you’re not prepared to lose fish.

You can introduce some other invertebrates at a lower risk. Shrimp (like Amano and Ghost varieties) should stay out of the way. Snails will too, Nerite snails are a popular choice for these brackish waters.

Keeping Fiddler Crabs Together

You can keep them together providing they have enough space. A group should only contain one male though, otherwise, they will fight. Keep at least a pair because they live in large groups in the wild and will get lonely on their own.

Fiddler Crab Food: What do Fiddler crabs Eat

When feeding in the wild, their claws are used to bring substrate to the mouth. They will then sift through the sand and eat anything nutritious, such as algae terrarium, and fungus. The rest of the substrate gets deposited in little balls.

They wouldn’t stray far from their burrow and only feed within a certain radius and then head back home.

In captivity, they will happily feed on foods that you add to the tank, most of which can be easily found in pet stores. Since they are omnivores you have a few choices.

Sinking foods aimed at scavengers (like shrimp pellets) will be collected as they explore the aquarium. Frozen foods are probably the most common part of the crab diet, things like frozen plankton and shrimp are nutritious and full of protein.

They will accept green vegetation too. Seaweeds, zucchini, and lettuce offer nutrients that prepared foods can lack.

Calcium is very important to include in a fiddler crab’s diet, they need it to develop new exoskeletons before molting. 

Once they molt, you should leave their exoskeleton in the tank for a week or so, as they might eat parts of it for the calcium. Remove the exoskeleton if it’s not being eaten.

Feed them once a day, giving a small mix of any of the foods above. This could be a couple of frozen plankton and a few shrimp pellets. You should mix up the foods at an interval of 2 – 3 days, perhaps switching to seaweed and bloodworms.

As a rule, if your tank develops the smell of ammonia, you’re feeding them too much.

Do Crabs Eat Their Babies

Only when female crabs are hungry, then they eat their own young babies.

Generally, a hungry parent also needs to eat to survive. According to recent research, female crabs that recently carried eggs, ovigerous, ate only 25 to 30% of their own larvae that they carried. 

Non-ovigerous crabs got their ‘eat-on’ by consuming an average of 90% of larvae. 

Fiddler Crab Care

Most health problems are caused by poor water conditions, so you need to keep your tank clean. Poor nutrition makes it harder for crabs to combat disease, so designing a suitable diet that provides a range of nutrients is a good way to prevent health issues.

Shell disease is one of the most common culprits which impacts their health. Bacteria, viruses, and fungi can cause colored lesions on the exoskeleton which can lead to internal damage too.

An individual should be able to cure themselves through molting.

Disease in captivity is rare as fiddler crabs are hardy. Most damage in the wild comes from fighting, but this shouldn’t be a problem with only one male in your tank.

Regular molts every eight weeks or so are natural and important. They do this to keep themselves healthy by removing ectoparasites or reforming lost limbs. After a molt, you will see the old exoskeleton sitting in your tank, don’t be fooled into thinking that they have died!

After a molt, they are particularly vulnerable because it takes time for their new exoskeleton to harden. You should keep a close eye on them until the exoskeleton hardens.

Breeding Season Gallery

They don’t mate like fish. Unfortunately, it’s not possible to breed your crabs in captivity because of how the larvae develop.

These larvae are planktonic, which means they spend a couple of weeks living in the ocean’s water column before heading back to shore.

There’s no way to accommodate this planktonic stage in your aquarium.

Your fiddler crabs might attempt spawning though. A male crab will court a female by using its claws to perform a series of signals.

The female tends to selectively pick an ideal male. Those with bigger claws are preferred because they can dig a larger burrow for the laying of eggs. 

You may see a female carrying egg in your tank, but just because you see eggs doesn’t mean that they will develop into adult crabs.

How To Buy

The first thing to note when buying a fiddler crab is that a lot of stores will list them as being freshwater crabs for sale. This is not true and keeping them in fresh water for an extended period of time will cause health problems and dramatically reduce crab life span.

If a store is keeping them in freshwater, either find a different store that’s keeping them in the right conditions or wait for a new shipment to come in (this will minimize the amount of time they spend in freshwater).

To ensure that you pick the healthiest individuals, check that they have all their limbs attached and that their color isn’t faded.

All the pet shops will not sell these crabs because usually they can not be kept as fish, however, a smart and quick search online may reveal a supplier near you.

Fiddler Crab for Sale

Expect to pay anywhere from $4 to $10 for a single crab. Prices vary with size, age, and store.

DIY Crab Trap: How to Catch Fiddler Crabs

Hey, It’s fiddler crab time!!!

Fiddler crabs are a preferred choice for pompano fishing. They are super easy to catch as long as you can find out an area that holds them.

If you plan to catch some fiddlers on your own, here are a few homemade crab trap bait items you will want to consider:

  •  Gloves – If you want to just grab these critters by hand it may be wise to wear a pair of gloves. They don’t have the biggest pinchers out there, but if they get you in the right spot you may shout a few choice words.
  • Small Bucket/Container – It is very easy to store fiddler crabs as they don’t require any maintenance. A small bucket with a tiny bit of water will do just fine. Be sure not to overfill with water. You want just enough that the crabs are kept wet but not submerged. To scoop the crabs up, a small bucket can also be used.
  • Sand Flea Rake – A sand crab rake is a very good tool to use to scoop the crabs up as they scatter on the land. It is also very useful for digging them up if they are burrowed in the ground. Make sure that you take them out of the rake very quickly and placed them into a container as they can conveniently crawl out.
  • Net – Also, a useful tool, as you will see in the video. If you can spook the crabs to the waterline you can easily scoop them out of the water with the net. It also gives you a temporary place to store them as you catch them.

Most of the people go out with a container or a small bucket and their bare hands and just pick the fiddler crabs up. It is the quickest and easiest way to go about it. The more you start catching your fiddler crabs, the finer-tuned your techniques will be.


What is special about a fiddler crab?

Fiddler crabs are a great way to protect our vital coastal wetland ecosystems. Through burrowing into the clay of marshes, they create a maze of tunnels that are able to aerate (add oxygen) the grasses of marsh and the seagrass meadows that are underwater.

Why is it called a fiddler crab?

A Fiddler crab also referred to as call crab, is one of the species that comprise the genus Uca (order Decapoda of the subphylum Crustacea). They are called “fiddlers” because the male holds one claw, which is bigger than the other, and it is shaped similarly to the violin. The female’s claws are quite tiny.

Are fiddler crabs harmless?

While the male’s main claw is huge but fiddler crabs aren’t particularly dangerous to handle. However, be cautious that the claws could snap easily.

Will fiddler crabs eat fish?

It’s not advisable keeping fiddler crabs inside a tank with fish or other species. They could attempt to capture fish to feed. The fiddler crabs must be handled as gently as possible, as this could cause stress to the animal. In addition, they may nip you with their claws, if you scare them.

Do fiddler crabs eat worms?

Fiddler crabs can be fed shrimp pellets and worms. You can also feed flake fish food hermit crab food or dry cat food that has been crushed.

Summary: Fun Facts About Fiddler Crabs As Pets

It’s very unlikely that you will be able to add these animals to a pre-existing tank. They have some unique requirements that mean they will likely need a new fiddler crab tank.

Setting up a 10-gallon tank is not too difficult, and you can use a larger tank if you have extra space. If you can keep the brackish water under the right conditions then you shouldn’t have any problems.

You must be careful if you’re keeping fish with your crabs. It’s not impossible to do but there will always be a risk here.

These crabs are a great option for someone looking for a change from fishkeeping. They create a completely different look and display some interesting behaviors.

Hey, have you ever tried keeping fish with your fiddler crabs in your aquarium? Let us know about your experience in the comments section below…


Dibyajyoti Bordoloi is the creator and author of FishCampRehab.com, a third-generation experienced fish keeper and owner of a successful pet breeding farm. He is also a member of the Center for Wildlife Rehabilitation And Conservation (Assam), the Marine Aquarium Societies of North East India, and the Kaziranga Nature Conservancy of Assam.

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