Betta fish and crabs: not a good match

In this post, we are going to talk about freshwater aquarium crabs as an option to be a betta tankmate. We are also commenting on crab’s tank requirements and 8 types of crabs that are a great addition to any aquarist.

Can bettas and crabs live in the same tank?

No, they can’t. Despite some owners relying on the calm temperament of their betta and the layout of their tank, it’s in their best interest that they aren’t kept together.

Why bettas and crabs aren’t good tankmates?

Most crabs aren’t going to be super aggressive towards fish unless they feel threatened. If your fish has a similarly-sized fish to the crabs and stays in the upper parts of the water column, there shouldn’t be a problem. Unless the aggressive behavior is coming from your fish.

This is the case with betta fish. Like crustaceans, betta fish are extremely territorial. They can also display aggressive behavior and are very curious. Moreover, they go up and down in the water column and they can scavenger for leftovers too. This could pose a threat to your crab and it might attack your betta.

If your crab is small, your betta might eat it. On the other hand, if your crab has a bigger and strong claw it may attack your betta, pinching their fins and causing fin rot. In the worst-case scenario, they might even kill your betta. So, it’s better not to try your luck!

Another thing to consider is their tank requirements. Despite some crabs sharing a similar temperature or being able to withstand a neutral pH, they might have requirements that differ from the betta’s like salinity and type of water, for example.

Therefore, bettas and crabs are definitely not a good match.

Habitat Setup

One of the easiest and most important aspects to cover when having freshwater crab species is to mimic their natural environment. Your new friend won’t get crabby in a 30-gallon tank. Some of them need land and water requirements. So, a big tank will provide lots of space for switching habitats.

This is vital for any species that aren’t fully aquatic. If you fail to fulfill this need, your crab can get sick or even drown, in the worst-case scenario. What you need is a paludarium tank!

Another thing to consider is salinity and pH. Some species prefer a low level of brackish water while others can live in both brackish and freshwater. For species that prefer an environment with high salinity, you must add a bit of marine salt into the water before introducing your crab. Various crabs also prefer an environment slightly alkaline. This hinders crab to be a prospective tankmate to your betta.

What is a paludarium tank?

A paludarium tank is an aquarium that has semi-aquatic habitat, in which you can include many more creatures than you would in your average aquarium. Although not difficult, creating a paludarium tank demands attention. Regardless of the environment, crabs like to scavenge, climb, burrow, and also hide.

Hence, they need decoration for both water and land. Plants, pipes, driftwood, caves are good options for decorations. Not to mention the sloping substrate to create the transition between both environments.

8 species of crabs to your tank

Although betta fish and crabs aren’t a good combination, there is still the possibility of you having crabs in a different setup. They are fun creatures to watch with unique beauty. Here, we are going to talk about:

  • Red Claw Crab;
  • Panther Crab;
  • Fiddler Crab;
  • Vampire Crab;
  • Thai Devil Crab;
  • Freshwater Pom Pom Crab;
  • Thai Micro Crab;
  • Rainbow Land Crab.



Red Claw Crab

Red claw crab is native to Asia and is found in brackish water and at a temperature between 70 and 88 F. As most crabs, they need land access and plenty of hiding spots. Although shy, these crabs will eventually explore the tank once they get comfortable.

As the name suggests, they have bright red claws and the rest of their body is in muted tones. Red Claw Crabs can measure about 4 inches wide with their leg span and their carapace is about 2 to 2.5 inches in size. They can live for up to five years.

Red claw crabs are omnivores and their diet consists of pellets, flakes, or a combination of both for nutrients. Their claws are sharp and powerful and they can also eat other crabs and fish. Hence, make sure tank mates are compatible.

Panther Crab

The panther crab spends most of its time underwater going to the land every now and then. The Panther Crab has a beautiful tan or beige color with black and brown spots all over its body. Most male panther crabs also have a single large claw. Females usually have smaller claws than males.

This species can reach between 3 and 4.7 inches wide and their large claw can do some damage as panther crabs are known to be very aggressive and not do well in groups. You can keep them in pairs as long as pay attention to their behavior.

Fiddler Crab

Fiddler Crab has a lot of personality. They can measure up 2 to 3 inches and have a large claw. In males, one of the claws is oversized and it’s used both to intimidate predators and for mating purposes. Their color ranges from vibrant hues to muted tones.

These crabs aren’t fully aquatic. They have gills and primitive lungs that allow them to live underwater and on land. Fiddle crabs require brackish water, a salinity between 1.001 and 1.008, temperatures ranging from 75 to 86 F, and a slightly alkaline pH of 8.0 to 8.3.

Vampire Crab

Vampire crabs are beautiful nocturnal critters that stand out in any tank setting. These crabs are deep purple with slight color variations. They feature pinkish claws with white dapples on their back and bright yellow eyes on top of their head. Their tank must be heavily planted as they feed on plant matter, and places to hide.

Vampire crabs are hardy crustaceans and can adapt to various water conditions. They prefer temperatures between 70 to 82 degrees and high humidity levels. Aggression can be a problem, so it’s best to keep them in a single-species tank.

Thai Devil Crab

Like other crabs, the Thai devil crab needs both dry land and water to thrive. These are freshwater crabs, so water conditions must be met. They can range from purple to bright red. They have long antennae-like eyes and are quite peaceful. However, they can become aggressive towards smaller fish, when threatened.

Thai Devil Crabs are omnivores, feeding on algae build-up and plant detritus. Brine shrimp and pellets are also good options for their diet. These crabs need plenty of hiding spots and soft sand so they can burrow themselves for safety.

Freshwater Pom Pom Crab

Freshwater Pom Pom crabs are quite rare and completely aquatic. Hence, the tank doesn’t need any land portions. However, it’s recommended that the water levels are kept low. Extra attention is needed with these crabs as they are known to be notorious escape artists.

They need temperatures between 68 and 78 F and a pH around 6.2 to 7.2. Pom Pom crabs are small crustaceans initially measuring less than an inch wide and they can grow up to 1.7 inches. One of their unique features is the patches of hair that grow on their claws. This hair makes it easier to collect food such as plant detritus and algae.

Thai Micro Crab

Micro Thai Crab, as its name suggests is very small measuring 0.4 inches wide making them one of the tiniest crab species in the aquarium trade. This can be a double-edged sword. They can become easy targets to other tank mates as a good snack but at the same time, micro Thai crabs have excellent hiding skills.

Sometimes these crabs can be difficult to spot since they are covered in a camouflaging grayish-brown color. Their tiny size allows them to hide virtually anywhere. They like to spend time staying safe among plants, driftwood, and rocks.

They don’t need a big tank and will do in a 5 gallons tank. They are happier in groups of five. Micro Thai crabs are peaceful creatures who can live in peace with small shrimp and other friendly invertebrates.

These freshwater crabs are omnivores and their legs are covered with tiny hairs that are used to capture food particles floating in the water and microorganisms such as algae or insect larvae.

Rainbow Land Crab

Rainbow land crab is the biggest crab among the species cited in this post. They can measure from 6 to 8 inches across the carapace. So, these crabs require a big tank.

Additionally, the Rainbow land crab spends a lot of time on land. Hence, they need a paludarium aquarium that can fulfill their needs in order to keep them healthy. They can spend a lot of time burrowing in the mud.

Rainbow land crabs can live both in brackish and freshwater. They are very colorful with their carapace covered in a deep blue or purple hue while their legs are bright orange, which creates a unique look. These crabs are scavengers eating anything from plant matter, pellets, bloodworms, fish meat to fruits.


Molting is the shed of crustacean old shells so a new one can grow according to its new size. It occurs throughout a crab’s life. After molting, crabs become very vulnerable as it takes time for their new shells to harden.

During this time, extra care should be taken as they can be prone to attacks and injuries. Therefore, hiding spaces are a must to safeguard your crab. Make sure you have soft sand so they can burrow, vegetation, and hiding spots.

If you see something that resembles a dead crab at the bottom of the tank, don’t worry. It’s the crab’s old shell. You can leave it there for a few days as crabs might feed on them given their calcium content.


Crabs and bettas aren’t compatible to be tankmates, since both are territorial. Bettas can go up and down the water column and they are curious fish. Consequently, your crab can feel threatened and attack your betta, leaving it seriously injured if not dead.

Other reasons for their incompatibility are the water requirements. Some crabs need brackish water, low salinity, slightly alkaline pH, which hinders the possibility of them living in the same tank.

But crabs are a lot of fun to watch and they are beautiful too! Perhaps you can have a different tank setup, like a paludarium, and enjoy your crab. Just pay attention so it doesn’t escape the tank!  If you like our post or have any questions, leave a message below.


Ehanna, R. (2022). Freshwater crab introduction care guide – Complete guide on everything you need to know about crab care guide: Appearance, diet, care, breeding, habitat, and tank conditions. Independently published, 45 p.