Freshwater aquarium crabs are an option that many aquarists overlook. They think about fish, shrimp, snails, etc.
But crabs are awesome!
These interesting critters have a ton of personality and are a joy to watch. They bring a unique feel to any setup you have, and we absolutely love them.
So where do you start?
Since not many people know the best options when it comes to freshwater crabs, we thought it would be a good idea to put together a list. It will help you see what species are out there, and figure out which ones you want for yourself!
Table of Contents
1. Fiddler Crab
Fiddler Crabs are adorable little crustaceans with a lot of personality. Only reaching a leg span of 2 to 3 inches, they don’t get very large at all. But that doesn’t stop them from behaving like a larger creature.
The most defining feature of this crab is its large claw. Males typically have one oversized claw that they use to intimidate potential predators. It’s also used to put on a show for mating purposes.
The look of these freshwater crabs varies depending on the species. The term “Fiddler Crab” actually refers to a larger genus that includes more than 100 distinct species. Some are covered in vibrant hues while others are more muted in tone. Either way, most have the same general size and shape.
Contrary to popular belief, Fiddler Crabs are not fully aquatic. They split their time pretty evenly between being underwater and relaxing on land. Interestingly enough, these crabs have gills and primitive lungs to support their lifestyle.
These crabs require brackish water to stay healthy. Salinity needs to be somewhere between 1.001 and 1.008. Temperatures should be between 75 and 86 degrees Fahrenheit. Meanwhile, the pH balance needs to be slightly alkaline, measuring between 8.0 and 8.3.
2. Thai Devil Crab
The Thai Devil Crab is a beautiful addition to a paludarium setup. Like other crabs, these critters need access to both dry land and water. These are freshwater crabs, so keeping them in good water conditions is relatively easy.
From an appearance standpoint, Thai Devil Crabs are stunning. They can take on a wide range of colors. The most common you’ll see is purple. Oftentimes, parts or their heads and claws will be covered in a contrasting bright red color.
On the top of their heads, you’ll find long antennae-like eyes. Despite their intimidating looks and name, these freshwater crabs are quite peaceful. They can show aggression towards smaller fish, but that usually only happens when they feel threatened.
Thai Devil Crabs are omnivores that will feed on aquarium algae and plant detritus. Protein-based snacks are good, too. They enjoy brine shrimp and will often eat leftover pellets that fall to the bottom of the tank.
Speaking of the tank, these crabs need hiding spaces. They do best when they have a lot of access to soft sand so that they can burrow themselves for safety.
3. Vampire Crab
Perhaps one of the most fascinating freshwater aquarium crabs you can get, the Vampire Crab is sure to the star of your tank. It has stunning good looks that stand out against natural backdrops.
These crabs are covered in deep purple. Some slight color variations can exist as well. Many crabs will feature pinkish claws or splotches of white on their back. Bright yellow eyes on top of their head round out their quirky appearance.
When fully grown, Vampire Crabs are only about 2 inches wide with their leg span. Their body is only about an inch across, making them very small.
Vampire Crabs require lush environments with access to both land and water. Both areas need to be covered in plants. Not only does the crab feed on plant matter, but the vegetation will provide cover.
As for water quality, these crabs are hardy enough to adapt to a range of conditions. They do best in temperatures between 70 to 82 degrees. High humidity is also a must.
These crabs are fittingly named. They are largely nocturnal and will spend most of the daylight hours hiding. Aggression can be a problem, so it’s best to keep this crustacean in a single-species tank.
Red Claw Crabs are another popular invertebrate in the aquarium community. They can be a bit shy and skittish. But, these crabs will eventually “come out their shell” and spend more time exploring the tank as they get comfortable.
These crustaceans come from Asia and are most often found in rivers leading to the ocean. Thus, they need brackish water to stay healthy. Water should have a specific gravity of around 1.005 and a temperature between 70 and 88 degrees.
Land access is also important. However, you don’t need as much of it as you might with other crabs. A water to land ratio of 3 to 1 is ideal.
As always, plenty of hiding places is preferred. Though, you should be wary of introducing too many living plants into their habitat. These freshwater aquarium crabs have a reputation for shredding and uprooting plant leaves!
Their claws are sharp and powerful. They’re fully capable of doing some damage. As their name would suggest, the claws are typically covered in bright red.
It’s a nice contrast to the muted tones of the rest of their body. Red Claw Crabs are moderately-sized creatures, measuring about 4 inches wide with their leg span. The carapace is usually only 2 to 2.5 inches in size.
5. Panther Crab
These intimidating crabs are an interesting addition to freshwater tanks. Unlike other crabs you’ll come across, the Panther Crab spends most of its time underwater. It will still need a small patch of land to get out once in a while, but they will spend most of their time living aquatically!
As long as you keep temperatures between 75 and 82 degrees, you should have no problem keeping the Panther Crab healthy. They’re quite hardy and adapt well to most habitats.
The Panther Crab is very beautiful. Its base color is tan or beige. However, they’re covered in spots of black and brown. Like Fiddler Crabs, most male Panther Crabs also have a single large claw. This is possible with females too, but their claws don’t get as big as the male crabs.
This species is one of the larger freshwater crabs for aquariums, measuring between 3 and 4.7 inches wide. As a result, their large claw is capable of doing some harm.
These crabs are known to be very aggressive and don’t do well in groups. They can be kept in pairs, but even then you must keep a watchful eye.
Freshwater Pom Pom Crabs are relatively new to the aquarium trade. They’re still quite rare. But if you can get your hands on one, they can be a joy to care for.
These crabs are completely aquatic. They spend all of their time submerged in the water, so you don’t need to create any land portions in your tank. We do recommend keeping the water levels low, though. Freshwater Pom Pom Crabs are notorious escape artists.
Overall, the crustaceans are not picky. To stay healthy, they need temperatures between 68 and 78 degrees. The pH balance of the water should be around 6.2 to 7.2.
The coolest part of Freshwater Pom Pom Crabs is their looks. These are small fish. Most will be less than an inch wide when you first get them. At most, they will get to be about 1.7 inches. That includes their legs!
While they may be small, they have some cool features. The most iconic is the patches of hair that grow on their claws. Food collects in the fibers, making it easy for the crabs to gather plant detritus and algae.
7. Thai Micro Crab
If you only have room for a small tank, the Micro Thai Crab may be the species for you. Their bodies only get 0.4 inches wide! They’re one of the tiniest crab species in the aquarium trade.
The crabs can be difficult to spot sometimes. They are covered in a camouflaging grayish-brown color. Thin spider-like legs do expand their size a bit, but their tiny size allows them to hide virtually anywhere.
Speaking of which, hiding spots are good for this species. They’re quite vulnerable to attack, so they like to spend time staying safe among plants, driftwood, and rocks.
You don’t need a very large tank at all. They do just fine in tanks as small as 5 gallons. It’s best to keep them in groups of five. The crabs can also live comfortably with small shrimp and other peaceful invertebrates.
As for diet, these freshwater crabs are omnivores. Tiny hairs cover their legs. They are used to capture microorganisms or food particles floating in the water. The crabs may also feed on algae or insect larvae.
8. Matano Crab
Hailing from Lake Matano in Indonesia, the Matano Crab has become quite widespread in the last couple of decades. They are relatively easy to care for and have a striking appearance.
These are large crabs, measuring about 3 to 5 inches with their leg span. The carapace is roughly 1.5 to 2.5 inches when fully grown.
Matano Crabs are much chunkier than some other crab species. They have a square-shaped body and a T-shaped abdomen. As for color, these crabs are covered in a bright purple. The joints around their legs are typically white, giving them a unique look.
The great thing about Matano Crabs is that they’re fully aquatic. They do just fine spending their entire lives without coming out. That said, they’re not afraid to do a bit of land exploration. Providing a small chunk of land is good, but it’s not a requirement for the crabs.
Water conditions are very important for the Matano Crab. Temperatures should be between 77 and 86 degrees. They need a slightly higher pH as well. It needs to be between 7.8 and 8.2.
9. Rainbow Land Crab
The Rainbow Land Crab is a behemoth compared to other species! Measuring 6 to 8 inches across the carapace, these crabs require a significant amount of space. Combine their size with their scavenging nature and it’s best to go with a large tank to keep them healthy.
To make things even more complicated, the Rainbow Land Crab spends a lot of time out of the water. They will need a healthy combination of water and land to thrive, but most of their time will be spent burrowing in the mud.
The good news is that the crabs do just fine with fresh water. They can live in brackish environments, but it’s not a requirement.
These are eye-catching aquarium crabs that have a lot of color. The carapace is typically covered in a deep blue or purple hue. Meanwhile, their legs are bright orange, creating a nice contrast.
Rainbow Land Crabs are easy to feed. They scavenge for plant matter. However, they will eat anything. You can provide pellets, bloodworms, fish meat, or fruits.
Helpful Tips For Owning A Freshwater Aquarium Crab
Since owning a freshwater crab is something that many people don’t have experience with, it’s worth spending some time on their unique requirements.
You see, these creatures are a bit different. As you can probably tell by the descriptions above, most need a unique habitat and have a spicy personality you need to be mindful of.
One of the most important aspects of caring for any freshwater crab species is to create the perfect environment. A cozy space that imitates their natural environment is a must. While you can do some research to learn more about your specific crab’s natural habitat, it’s not hard to cover the basics.
First, you need to ensure that the tank is big enough! Some owners keep crabs in single-species tanks that are only 10 gallons in size. This is fine for smaller crabs that are only a few inches wide. However, you may need to bump that up to 30 gallons if you’re going with a larger species like the Rainbow Land Crab.
Next, you’ll need to learn more about your crab’s land and water requirements. Not all crabs are fully aquatic. In fact, most of them split their time pretty evenly between land and water living.
This is a crucial consideration that you need to accommodate. If your crab belongs to a species that spends a significant amount of time on dry land, you need to provide that space. Otherwise, your crab could become ill or even drown!
Luckily, creating land spaces isn’t too difficult. You can create a paludarium tank with a floating perch or sloping substrate. Alternatively, you can use shelves to make dry areas more accessible to your crab.
Now, creating land and water environments can be tricky. Not only do you have to stay on top of water conditions, but the land portion needs attention. Depending on your crab species, you may need to invest in heaters or humidifiers to keep your pet healthy.
As for tank decorations, crab prefers a lot of variety. Whether they are underwater or on dry land, crustaceans are big explorers. They like to climb, burrow, and scavenge. Plus, they need places to hide.
Consider filling your aquarium with live plants, driftwood, and rocks. These natural decorations can help your crabs feel safe. Artificial decorations, such as PVC pipes, overturned clay pots, and plastic shelters, all work, too.
General Water Conditions
Required water conditions can vary from species to species. However, most of the critters you see in the aquarium trade are going to need similar tropical environments.
Typically, freshwater crabs do best in temperatures ranging from 72 degrees up to 82 degrees. The required pH balance is going to be a bit more specific depending on the species you have.
Whatever the case may be, make sure to filter out the water first. Crabs can be particularly sensitive to chemicals in tap water, such as chlorine.
Another thing to consider is salinity. Some species prefer a very low level of brackish water. In these cases, you would need to incorporate a bit of marine salt into the water before introducing your crab.
For the most part, crabs are easy to feed. They’re omnivores that will consume most of the foods you provide. These creatures are largely opportunistic, so they won’t shy away from snacks.
Many freshwater crabs will feast on plant detritus or eat algae during the day. You can supplement this with blanched vegetables like zucchini or lettuce. Commercial foods are good, too. Algae wafers and sinking pellets are always a good choice.
Protein-based foods are important as well. You can provide snacks like bloodworms, brine shrimp, insect larvae, and more.
Crabs are unique in the fact that they need calcium. You can provide crab-approved calcium supplements or shellfish to meet this need. The calcium is meant to strengthen their shells and help the creatures recover after molting.
Most crabs are not going to be super aggressive towards fish (especially if they can’t get near them). Of course, there are always exceptions. But for the most part, fish stay out of their way.
As long as you get similarly-sized fish that stay in the upper parts of the water column, you shouldn’t encounter any issues (they’re not a good fit with freshwater snails).
That said, you do want to be careful about aggressive behavior coming from your fish. Crabs are often a target for larger fish species. Cichlids, for example, have been known to attack crabs because they view them as snacks!
When you’re planning a community tank, always keep your specific crab’s size and temperament in mind.
Crabs often show aggressive behavior towards other crabs as well. This could be crabs of different species and crabs of the same species.
Crustaceans are notoriously territorial. The best way to avoid aggressive behavior is to incorporate plenty of hiding spots and invest in a large tank. If every freshwater crab kept in an aquarium has its own space, fighting will be kept to a minimum.
Molting occurs several times throughout a crab’s life. It’s when they shed their old shell to make room for a new one.
The interesting thing about molting is that crabs are very vulnerable afterward. It takes time for their new shells to harden completely. During this time, they are prone to attacks and injuries.
That’s why it’s so important to implement hiding spaces. Crabs are fully aware of their vulnerability, so they will spend time looking for cover after molting.
If you see what appears to be a dead crab body at the bottom of the tank, don’t fret. Leave it there for a couple of days before removing it. Some crabs will feed on their old shell for the calcium!
Ready To Become A Crab Owner?
Now that you know all the different types of freshwater crabs, it’s time for you to decide if they’re right for you.
While the unique needs of these creatures might seem intimidating at first, it’s nothing to be scared of. In fact, it’s all part of the fun!
We’ve been involved with the aquarium community for quite a while, and crab owners are some of the most passionate people we’ve ever met. They’re completely in love with these critters and would never consider going without one!
If you’re looking for something a little different, you should definitely consider one of the freshwater crabs from our list.
You won’t regret it!