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Spice Things Up With The Fiddler Crab

Are you sick of staring into your aquarium tank, watching your boring fish swim around in the same patterns day after day? While keeping fish is certainly an enjoyable hobby to have, you have to admit that keeping the same species of fish all the time can get a little bit dull.

If you’re sick of the same-old, same-old, it might be time to upgrade your tank by adding a non-fish species. There are plenty to choose from, with options including frogs, shrimp, and snails. However, have you ever considered adding a crab?

Many people keep crabs in their freshwater aquariums. If you’re interested in keeping paludarium, which includes land and water ecosystems, crabs are the perfect species to include. As invertebrates, they get along well with common species of fish. They also have entertaining behaviors and are surprisingly easy to care for.

Ready to learn more? If you’re ready to spice things up in your aquarium, it’s time to consider raising one of the best crab species for your freshwater tank: the Fiddler Crab.

Fiddler Crab

Fiddler Crab Background

Fiddler Crabs are unique organisms that belong to the Ocypoidade family. Along with ghost crabs, this large group of crustaceans is also known as calling crabs. There are over 100 different species that are all referred to as Fiddler Crabs and belong to the Uca genus. While each separate species has its own quirks and care requirements, this article will cover the basics in caring for all kinds of Fiddler Crabs.

These funny-looking creatures are found all around the world. You can find Fiddler Crabs on both sides of the Atlantic as well as in the Eastern Pacific and the Indo-Pacific region. Fiddler Crabs prefer to inhabit coastal environments with brackish water, and can generally be found in mangroves, muddy beaches, or salt marshes.

Fiddler Crab 1
Photo by Eric lynch

Often marketed as freshwater species, this is somewhat of a misnomer. While you can keep Fiddler Crabs in freshwater with some success, this can be damaging to their health in the long term and won’t allow for ideal longevity. When cared for properly, Fiddler Crabs can live for up to three years in captivity. They can tolerate basic missteps in caregiving and will get along well with your other species.

Fiddler Crabs are not difficult to care for, but if you have only ever cared for fish in your aquarium or paludarium, there are some guidelines you will want to keep in mind. For example, Fiddler Crabs molt on a regular basis, which can be quite intimidating to witness if you have never seen this happen before.

Fiddler Crabs typically live on the coastline and are therefore well-suited to dealing with ever-changing conditions. They need to adapt to change in the tide as well as the natural movement of the water. This is why Fiddler Crabs can survive on both land and in water. They like to live in areas that have sandy substrates and plenty of rocks to hide between.

Fiddler Crab Appearance And Behavior

Fiddler Crab 2
Photo by Decineper

One of the most attractive crab species you will find, the Fiddler Crab is easiest to identify by looking at its large claws. Males have one minor and one major claw, the larger of which is usually used as a tool. Females will only have two minor claws.

Behind the sets of claws, these crabs will have four more pairs of legs. These are used for mobility. Fiddler Crabs also have shells that are covered in hard coatings. These coatings help to protect the crabs from attackers. They also have a carapace, which is a hard plate that protects the main body and internal organs.

Fiddler Crabs are quite entertaining to look at head-on. They have two eyes and a pair of antennae that stick out quite noticeably from their heads they use their antennae to collect information about their surroundings.

Most Fiddler Crabs are quite small, only growing to about two or three inches in small. You can occasionally find larger varieties of this species, but usually they will be tiny.

The color of your Fiddler Crab will vary depending on the stock that you select. Usually, Fiddler Crabs won’t be as colorful as the fish in your tank. They tend to be orange or brown, but some do have more distinctive color patterns or features. For example, Uca perplexa, a popular type of Fiddler Crab, has one bright yellow major claw that stands out sharply against the rest of its brown body.

Males and females are easily distinguishable. Not only do males have a large major claw, but females will also be noticeably smaller than their male counterparts.

Fiddler Crabs are unique in that they can survive (and thrive!) both in and out of the water. They are referred to as semi-terrestrial species, meaning they will split their time evenly between water and land. These creatures have gills and a basic lung, which allows them to breathe in either setting.

Fiddler Crabs also have unique claws. These claws serve multiple purposes. They use them to attract females, dig burrows, or fight with other males. You will often see these creatures raising and then lowering their claws. This is often regarded as the Fiddler Crab’s method of communicating with other fiddler carbs. They will give different signals depending on how far away they are from each other.

Fiddler Crab 3
Photo by Alex Voets

These carbs are peaceful organisms. Usually, you will only witness fighting or other aggression during the mating period. Even then, fighting is typically only common between competing males and will not be seen among females. A common method of intimidation that is used among males is known as dishonest signaling. When a male loses a claw, the one that grows back will usually be much weaker. However, the crab will continue signaling with that claw in order to intimidate other, stronger crabs.

Both males and females have claws, but males are the only ones with major claws. They cannot use this major claw to eat, as it is designed for breeding and fighting, and so females are much more efficient eaters. Regardless of gender, each crab has ten feet and can change its color in response to social and environmental conditions.

Fiddler Crabs shed their exoskeletons every eight weeks. The mourning process is normal, and it can be quite the affair to watch. What is unique about this species is that it can completely regenerate itself. Even if it loses a limb, it can grow a brand-new one by the time the next molt has completed.

Fiddler Crabs have unique behaviors that will make up most of their days. They are detritivores, meaning they eat detritus. Therefore, they will spend much of their days removing and then eating dead matter from the substrate.

Fiddler Crab Tank And Water Requirements

Fiddler Crab 4
Photo by Michael Aagaard

Fiddler Crabs, as previously mentioned, can adapt easily to a wide variety of water conditions, as this is what they are acclimated to in the wild. They like warm, slightly alkaline waters and prefer to have waters that are well-aerated and always moving. Setting up a tank to accommodate for these conditions is not challenging, but it does require a bit of effort.

Begin by adding a layer of soft, silty substrate to the bottom of your tank. Sand is a good choice as a substrate, because it will allow the crabs to burrow and feed in the sand. It should lead to a raised area of the tank. This should sit just above the surface of the water so that your crabs also have access to land as well as to the water.

Rocks and other decorations are crucial in a Fiddler Crab habitat. These will help provide places to hide, as w\ill plants. Artificial plants are the best choice for Fiddler Crabs, as they have a habit of destroying any live plants they come into contact with.

When you are setting up your tank, resist the urge to fill it up to the top with water. Air is just as important to a Fiddler Crab as is water, so you should only fill it about a fifth of the way with water before providing a sandy slope with an area above the surface.

What’s particularly challenging about keeping Fiddler Crabs in captivity is that they need brackish waters. This can be challenging, as most people are used to keeping freshwater in their tanks try to keep the salinity of the tank between 1.01 and 1.08 for best results.

The water temperature should be around 75 to 86 degrees Fahrenheit, with an ideal pH between 8.0 and 8.3 Water hardness should be maintained at or around 15 KH. Fiddler Crabs need relatively high oxygen levels, so it might be necessary to aerate the tank with either a strong filter outlet or an air pump.

When you are keeping Fiddler Crabs, provide at least ten gallons for every one to four crabs. For every grab that you add, you will need to supply an additional three to five gallons. Make sure you do not overcrowd your Fiddler Crab tank. Crabs that are too crowded will decline in health, as too many crabs increases the likelihood of water pollution.

What Do Fiddler Crabs Eat?

You don’t need to do much extra work when it comes to feeding your Fiddler Crabs. In the wild, these creatures will use their large claws to gather the substrate to their mouths. There, they will sift through and eat anything they can find an ndt aht is nutritious. Popular choices include fungus and algae. Once they have eaten everything they can, they deposit the rest of the substrate in small balls.

These creatures don’t usually stray too far from the burrow. They will only feed during certain times of the day and within a specific radius from their homes. After that, they will head back home to hide and relax.

If you are raising a Fiddler Crab in your tank, know that they will happily eat most of the foods you add to your tank, typically the same kinds of foods you can feed to your freshwater fish. They are omnivores, which means you will have lots of choices in how you choose to feed your crab.

Usually, foods aimed at scavengers that sink will be the best bet for Fiddler Crabs. Shrimp pellets, for example, should form a core of this creature’s diet. You could also feed frozen foods like plankton and shrimp.

Because Fiddler Crabs are omnivores, they will also eat green vegetation. They prefer natural foods like lettuce, seaweed, and zucchini. You can feed these cooked, fresh, or frozen.

If you’re used to feeding fish in your freshwater aquarium, feeding your Fiddler Crab won’t be radically different. However, the thing to keep in mind is that your Fiddler Crabs will need supplemental calcium. Calcium helps the Fiddler Crab develop a new exoskeleton before it molts. After the Fiddler Crab molts, it is advised that you leave the skeleton in the tank for a week or so to provide a source of calcium and food to the Fiddler Crab. Once it looks as though the Fiddler Crabs aren’t nibbling on the exoskeleton any more, you can remove it from the tank.

These creatures should be fed once a day, providing a small mixture of the foods we have mentioned. For example, you might feed a couple of bloodworms and a few shrimp pellets. What’s even more important is that you switch up the kinds of foods being offered every couple of days. For example you could switch to bloodworms and then back to sweated. This variation will prevent your Fiddler Crabs from becoming bored and will also ensure that they are getting all the nutrients they need.

Watch your Fiddler Crabs carefully to observe how much food they are eating. If your tank begins to smell, it’s a sure sign that you are feeding too much and need to back off on the portion sizes or feeding regularity.

Fiddler Crab Tank Mates

If you’re thinking of adding Fiddler Crabs to your community tank, know that it can be done but that you will face additional challenges in getting it set up. Because most freshwater fish can’t survive in brackish waters, it can be difficult to find the perfect tankmate. In many cases, even when you do find a freshwater fish species that can thrive in a brackish community, the crabs will attack the fish or larger fish will, in turn, attack the crabs.

One good choice of a companion to consider is the molly. These fish can thrive in low salinity but are often too big for crab tanks – unless you are willing to invest in a tank that is thirty gallons or larger. You might also consider spies like swordtails, platies, guppies, or bumblebee gobies.

While there are numerous species of crabs that will help you meet your needs, what you need to remember is that any fish you choose to include has to be fast and able to hold its own against the claws of a Fiddler Crab. These crabs aren’t known to frequently attack other creatures, but they have the potential to be quite deadly with their massive claws.

You could also add creatures like other invertebrates to your tank. These offer a lower risk, and creatures like amano and ghost shrimp as well as nerite snails will usually stay far away from your Fiddler Crabs.

When in doubt, considering keeping a tank of just Fiddler Crabs. These creatures get along well with each other, and as long as you have enough space, you shouldn’t have any problems. Remember to mind your gender ratios in your groups of Fiddler Crabs however each group should only contain one male because more than one male will fight. Even if you don’t want to keep large quantities of Fiddler Crabs it’s a good idea to keep at least two together as they live in large groups in the wild. They have a tendency to become lonely when left on their own.

Common Fiddler Crab Diseases

Fiddler Crab 5
Photo by Hiwystar

Fiddler Crabs are easy to care for, but there are some health issues that can come about as the result of poor care and water quality. Shell disease is one of the most common issues. This arises as a result of viruses, bacteria, or fungi in the water. This disease creates colored lesions or ulcers on the exoskeleton of the crab. This can also cause internal damage if left untreated. Luckily, most Fiddler Crabs are able to relieve themselves of this disease through the process of molting.

Captive crabs rarely develop diseases because they are so hardy. In the wild, Fiddler Crabs frequently injure themselves from fighting, but if you are careful to only keep one Fiddler Crab in your tank, you shouldn’t have to worry about this.

Regular molting can also help to keep your Fiddler Crab help. You should expect this to occur every eight weeks or so. Molting helps to remove ectoparasites and to repair injured or lost limbs.

Keep in mind that although molts are natural and can be made even healthier by adding extra calcium to your Fiddler Crab’s diet, your crab is particularly vulnerable after a molt because it takes some time for a new exoskeleton to appear. Keep a close eye on your crabs during this time, as they will be particularly susceptible to injury.

Breeding And Life Spans Of Fiddler Crabs

Fiddler Crab 6
Photo by Roaming Together

If you’re interested in breeding your Fiddler Crabs, be aware that this often is not possible when you are raising the tiny creatures in captivity. Larvae develop in a unique way, as they are planktonic. This means that they spend several weeks living in the ocean before they head back to shore. Because you won’t be able to replicate this stage in your aquarium, you will not be able to breed Fiddler Crabs in captivity.

That being said, you may be able to watch your Fiddler Crabs attempt spawning. This is done when males court females by utilizing their claws to conduct a series of intricate signals. Females will pick an ideal mate, typically those with larger claws as they will be better-suited to dig a burrow for egg laying. Females may also sometimes carry eggs, but they will rarely develop into adult crabs.

Is a Fiddler Crab For You?

Think you might not have what it takes to raise a Fiddler Crab? Think again. These delightful creatures aren’t just easy to care for, they’re incredibly fun to watch. They don’t take up much space with their small size, but they also have claws that grab your attention immediately. These adorable creatures have powerful claws that offer a unique attraction to your tank.

If you’re looking to buy a Fiddler Crab, note that although many stores list them as freshwater species, keeping Fiddler Crabs in freshwater can actually damage their health over time. Instead, you should pick the healthiest individuals and keep in mind that you will need to provide a brackish environment in your fish tank.

Fiddler Crabs are one of the best invertebrates you can keep in a fish tank. A great introductory species for beginners, they are the ones that can add some serious interest and personality to any tank.

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