Fish and shrimp aren’t the only interesting creatures you can keep in a tank. Keeping crabs can be just as, or even more fascinating. Many small species of crab can even be kept in freshwater or slightly brackish tank setups, so there’s no need to invest in a full saltwater kit for your aquarium.
Therefore, if you are interested in keeping crabs. Below I have listed 7 of the best crab species suited for freshwater tanks’ life. Whether you are new to crab keeping, or you are an old pro these 7 crab species won’t disappoint.
Without further ado let’s start.
1. The Thai Micro Crab (Limnopilos Naiyanetri)
The Thai Micro crab is native to a single river in Thailand and lives up to its name with an adult size of less than an inch in diameter. This crab is also known as the False Spider crab, Micro crab, Pill-box crab, etc due to its tiny size and unproportionately long legs.
These crabs are partially filter feeders. They use the small bristle like hairs that cover their body to catch detritus particles and other microorganisms. As water passes through their hair, the small particles become trapped. In a well-established tank, these crabs will need very little, if any supplemental feeding.
Thai Micro crabs are greyish brown in color and they tend to be quite shy. It is common for these little crabs to spend most of their time hiding. Thai micro crabs can coexist in peaceful community tanks (read more about community tank here). They are social and enjoy living in small colonies with other Thai Micro crabs. Dwarf shrimp species, snails, and some kinds of small unaggressive schooling fish also make good tank mates for Micro crabs. Their small size and docile nature make them easy prey for larger fish and even other crab species.
Thai Micro crabs are fully aquatic and spend their entire lives submerged. They prefer heavily planted, or densely decorated tanks with plenty of hiding places. In their natural habitat, they spend the majority of their lives hiding out in the roots of floating plants, like the water hyacinth.
2. The Pom Pom Crab (Ptychognathus Barbatus)
Pom pom crabs get their name from the unique filter hairs on their claws that make them appear as if they are always holding pom poms. They are Native to the Hawaian Islands and are fairly uncommon in the mainstream pet trade, but they are worth hunting for. Pom pom crabs are small and only reach about 3.5 – 5 cm (~1.5 – 2 inches) in diameter full-grown (across the leg span).
These crabs are absolutely peaceful filter feeders and can safely exist in a community tank with anything that won’t eat them. They pay no mind to and won’t bother even the smallest of tank mates, making them a great addition to Nano tanks.
Pom pom crabs are fully aquatic and easy to care for. They do not have any special housing requirements besides the fact that they are burrowers. They will enjoy a planted tank or any tank with lots of hiding spots.
Unlike many species of freshwater crabs, Pom pom crabs are very active and not shy creatures. They will boldly explore your tank day and night.
3. The Vampire Crab (Geosesarma Sp.)
Vampire crabs are a very unique and rare species of crab. Their name alone is an attention grabber, but they do not suck blood. The Vampire crab gets its name from its glowing yellow eyes and striking colors, ranging from a deep purple color, to neon orange. Arguably, the most beautiful crab on this list, Vampire crabs aren’t very common in the aquarium hobby. This is mostly due to being exceptionally hard to find.
Vampire crabs are not fully aquatic, in fact they are mostly terrestrial. They require a special tank set up, called a paludarium that offers them more dry land space than water. However, they are included in this list because they still require a fairly large source of freshwater anyway.
A good land vs water ratio for a small colony of Vampire crabs in is 2/3 land to 1/3 water. This can be adjusted further in larger tanks to accommodate larger colonies. Keep in mind that Vampire crabs are rather small, with a diameter of barely 5 – 6 cm (~2 – 2.5 inches) across the leg span at their adult size.
Vampire crabs are omnivores and will gladly eat just about anything they can get. From vegetation, like algae, to commercial crab (fish or shrimp) pellets (flakes, granules, etc) and even live insects, such as crickets.
Another good thing about Vampire crabs is that they are generally non-aggressive to one another.
4. The Tanganyika Crab (Platythelphusa Sp.)
The genus contains many species, which are often confused for one another and mislabeled. Platythelphusa sp. includes Armata, Echinata, Polita, Praelongata, Platynotus, Denticulata, Tuberculata, Maculata, Conculata, and Immaculata. The largest of these is Armata, which reaches 6 cm (~2.5 inches) in diameter.
Tanganyika crabs can be kept in small colonies in a larger tank, it is not recommended to house many males together though. Tanganyika crabs are not community tank friendly, they are omnivores like most crab species and they will eat anything they can get a hold of, including fish, shrimp, snails other (weaker) crab species, and any other slow swimming tankmates. However, some hobbyists have had luck housing these crabs with fast swimming Tanganyika cichlid species.
According to different studies, adults live at depths of 5–30 meters (16–98 ft), meaning that Tanganyika crab is one of the few fully aquatic crab species.
These crabs are better suited to more advanced aquarium keepers, due to the lack of information surrounding their specific needs and their tendency to be mislabeled by vendors in the aquatic pet trade.
5. The Panther Crab (Parathelphusa Pantherina)
Panther crabs are native to Sulawesi and are a more difficult variety of aquarium crabs. They get their name from their orange, spotted panther like appearance. At their adult size they can reach a diameter of 3 – 8 cm (~2 – 3 inches), or slightly larger. They are one of the largest aquarium crabs and they require large tanks (a 20 – 30-gallon tank will comfortable house only 1, maybe 2 crabs).
Panther crabs do not do well in large groups, or community tanks. They are territorial and aggressive, even to their own species. It is recommended to only keep these crabs in male/female pairs, female/female pairs, or small harems. Males will readily seek out and fight one another. Panther crabs are omnivores and will happily eat anything they can get a hold of, including their smaller tankmates.
These crabs are fully aquatic but will not mind to have a source of dry land. Keep this in mind, while also ensuring the tank has a tight fitting lid. Given the chance, panther crabs will escape and you don’t want them exploring your house freely.
6. The Matano Crab (Syntripsa Matannensis)
Also native to Sulawesi, the Matano crab is just as colorful as the Panther crab. There are two known varieties of this crab species, with one being almost black and the other having a purple carapace and bright yellow legs. They are a rare find in many big-name pet stores, but can be found in online shops and through private vendors.
Matano crabs are a large crab species and require large tanks. Full-grown they can reach a carapace diameter of up to 12 cm (~5 inches). Keep this in mind before choosing to keep these crabs as a harem can easily require a 20-gallon tank (~90 liters), or larger.
Like the Panther crab, the Matano crab is a predatory crab that leans towards the aggressive and territorial side. They don’t do well in multiple male groups, or in community tanks where their tank mates may become their next meal. Harems, or male/female pairs are recommended. Larger, fast-swimming fish species can be kept with Matano crabs in some cases, however, avoid keeping them with snails, shrimp, slow swimming fish, or still sitting fish, like algae eaters.
Matano crabs are fully aquatic and do not require a source of dry land. However, they are not afraid of and are capable of leaving the water. They will escape if given the chance.
7. The Rainbow Crab (Cardisoma Armatum)
Rainbow crabs are native to West Africa and get their name from their vivid, contrasting colors. They range in color from blue to purple, with orange to red legs. They are always easy to spot and will make a visually appealing addition to your tank.
The males tend to be more colorful than females and full-grown they reach a carapace diameter of 10 cm (~4 inches) on average. Though, a few specimens have been reported to have reached 6 – 8 inches across. Because of their size, an individual rainbow crab requires at least a 20-gallon tank for 1 crab. Housing multiple rainbow crabs will require a large tank.
Rainbow crabs are burrowers and enjoy having a thick substrate that they can dig in, such as sand, or a sand/soil mixture. They are not fully aquatic crabs and will require a piece of land.
Rainbow crabs are not overly aggressive, but males will fight. They are omnivorous scavengers and will eat just about anything. Their preferred diets consist of fruits, vegetables, fish, pinkies, bloodworms, crab pellets, cuttlefish, and unlucky tank mates.
They can get fairly large, so it is not a good idea to keep them with small fish, aquarium snails, shrimp, bottom feeders, or other tank mates that they could make a meal of. They have been observed ambushing unsuspecting fish from their burrows, so it is especially important to avoid housing them with fish species that prefer to eat food that has fallen to the bottom of the tank.
All of the crabs on this list make amazing pets when cared for properly. From active colorful crabs to shy and docile crabs they all have something unique to offer. No matter which species of freshwater crab interests you, or the amount of experience you have in keeping crabs, it is always important to fully research any species before introducing it to your tank.
Adult size, temperament, diet, and habitat needs all play a role in successfully keeping any kind of crab. You wouldn’t want your new crab(s) to eat, or be eaten by another member of your tank.