Tanganyika Crabs – Detailed Guide: Care, Diet, and Breeding

The Tanganyika сrabs (Platythelphusa Sp.) are one the rarest crabs in the aquarium hobby. If you by chance buy one you will be surprised to find out how little is known about them.

The Tanganyika сrabs require a properly set up tank. Therefore, you will have to make sure your water parameters stay high quality at all times. Based on this, I would say that these crabs are best left in an aquarium with an experienced aquarist.

In this article, I have gathered all information about different species belonging to the genus Platythelphusa. It covers all aspects, from natural habitat conditions and how Tanganyika сrabs should be cared for within your aquarium, to dietary requirements and behavior aspects.

Quick Notes about Tanganyika Crabs

Name	Tanganyika сrabs
Other Names	African crabs
Scientific Name	Platythelphusa Sp.
Tank size (recommended)	10 gallons (~40 liters)
Type	Freshwater
Keeping	Medium
Breeding	Difficult
Average size (carapace)	up to 2.5 inches (6.5 cm)
Average size across the leg span	4 – 5 inches (about 10 – 12 cm)
Optimal Temperature	77 – 81 °F (25 – 27 °C)
Optimal PH	7.0 – 8.5
Optimal GH	10 – 20
Optimal KH	7 – 10
Nitrate	Less than 20 ppm
Diet	Carnivore/omnivore
Temperament	Aggressive
Life span	up to 5 years
Color Form	Brown to grey

Taxonomy Problems of Tanganyika Crabs

All freshwater crabs from Africa were initially referred to as a single family, the “Potamonidae”. Thus, the number of valid species within the genus Platythelphusa has been a subject of debate for many decades!

Note: The general neglect of African freshwater crabs over the years means that today their taxonomy is unstable and unreliable, species lists are inaccurate, distribution patterns are largely unknown, and little is known of the population levels or conservation status of most species in the region. Inadequate keys also make identification difficult for non-specialists.

The genus Platythelphusa shows extensive morphological disparity. A few species of Platythelphusa exhibit such morphological characters that are considered atypical for freshwater crabs and bear a striking resemblance to certain marine crabs.

Note: According to the study, the evidence supports a hypothesis for the evolution of this family from freshwater crab ancestors.

In 1887, these freshwater crabs were considered so distinct from the other crab species known up to that time that they were placed in a new genus, Platythelphusa armata. The description of this species was soon followed by the discovery of more endemic species from the lake that were described.

Over the years, some other species were added, removed, and even restored by different scientists because all these species are distinctly different with regard to a combination of characters from the carapace, chelipeds, and pereiopods.

Currently, the total number of Platythelphusa species from Lake Tanganyika is nine:

Platythelphusa armata – (categorized as least concern by the IUCN)
Platythelphusa conculcata – (categorized as least concern by the IUCN)
Platythelphusa denticulate – (categorized as vulnerable by the IUCN)
Platythelphusa echinata – (categorized as least concern by the IUCN)
Platythelphusa immaculata – (categorized as near threatened by the IUCN)
Platythelphusa maculata – (categorized as least concern by the IUCN)
Platythelphusa polita – (categorized as least concern by the IUCN)
Platythelphusa praelongata – (categorized as vulnerable by the IUCN)
Platythelphusa tuberculata – (categorized as least concern by the IUCN)

Etymology of Tanganyika Crabs

The name ‘Platythelphusa’ is probably derived from arbitrary combinations of letters, or from Greek roots. From ancient Greek πλατύς (platús, meaning ‘Flat’) and Θέλπουσα – it is an Arcadian nymph in Greek mythology. Her father was the river god Ladon.

Note: Generally, the word ‘Thelphusa’ is associated with freshwater crabs.

The specific name ‘Immaculata’ is derived from the Latin adjective “Immaculatus’,” meaning unstained or spotless.
The specific name ‘Praelongata’ is derived from the Latin adjective ‘Praelongus’, meaning very long, referring to the elongated pereiopods of the species.
The specific name ‘Armata‘ is derived from Latin ‘Armatus’, meaning Armed, and refers to the numerous spines, which gave its name.
The specific name ‘Conculcata’ is borrowed from Latin ‘Conculcatus’, meaning to tread or trample underfoot.
The name “Denticulate’ has Latin roots from dēns (“tooth”) +‎ -Culus (diminutive suffix) – ‘Small tooth’.
The specific name ‘Echinata’ is derived from the Latin word Echinatus, meaning bristly or prickly.
The specific name ‘Maculata’ is from Latin ‘Macula’ for spotted; referring to its blotched color pattern on the carapace of the crab.
The specific name ‘Polita’ is borrowed from the Latinate past-participle of the verb ‘Polire’ which is ‘Politus’, meaning ‘polished’ or ‘smoothed’.
The specific name ‘Tuberculata’ is presumably from the Latin ‘Tuberculatus’ (= tuberculate), referring to a tuberculate dorsal surface of the carapace of the species.

Habitat of Tanganyika Crabs

Species of the genus Platythelphusa are endemic to Lake Tanganyika (East Africa) which is bordered by Burundi, Tanzania, Zambia, and the Democratic Republic of Congo.

These crabs are generally found in rocky littoral areas. However, even on smaller scales substrates can be patchy (boulders, cobbles, pebbles, and sand).

Platythelphusa armata is mainly found in rocky areas, at depths between 16 – 100 ft (5–30 m) deep. The juveniles are found in the sublittoral shell zone from 10 – 30 ft (1–10 m) deep.
Platythelphusa conculcata is found in depths between 65 and 200 ft (20 – 60 m) deep.
Platythelphusa echinata is found in waters from 16 to 100 ft (5–30 m) deep, where the lake bed is sandy or rocky.
Platythelphusa immaculate is mostly collected from underneath rocks and cobbles at depths ranging from 6 – 65 ft (2 – 20 m).
Platythelphusa maculate is generally found in deep waters 65 – 520 ft (between 20 and 160 m).
Platythelphusa polita occurs in waters from 16 – 200 ft (5 – 60 m) deep, where the bottom is either sandy or rocky.
Platythelphusa praelongata is collected in deep waters between 130 and 260 ft (40 – 80 m).

Interesting fact: Lake Tanganyika is the oldest and deepest lake in Africa. It occupies a unique position among the Rift lakes. With an estimated age of 9-12 million years and a maximum depth of 1470 meters.

Description of Tanganyika Crabs

Understanding a bit about the different types of Tanganyika crabs you can choose from is actually very important because these species vary in coloration, shape, and maximum size of the carapace.

For example, according to the study:

Species	Adult size (Carapace size)	Color
Platythelphusa armata	up to 2.5 inches (6.5 cm)	Yellow-green mottled with reddish brown or violet spots.
Platythelphusa denticulata	up to 1.7 inches (4.5 cm)	Similar to that of P. armata.
Platythelphusa tuberculata	up to 1.6 inches (4 cm)	The carapace is light brown, the edges darker than claws and legs.
Platythelphusa maculate	0 up to 0.6 inches (1.5 cm)	Grey-brown mottled with red. A few spots on the anterior region of the ventral face.
Platythelphusa polita	up to 0.7 inches (1.8 cm)	The carapace is dark brown with small reddish spots and a light ventral side.
Platythelphusa echinata	up to 0.8 inches (2.1 cm)	The carapace is light brown and speckled with reddish-brown spots; the face ventral is not spotted.
Platythelphusa conculcata	up to 0.9 inches (2.2 cm)	Similar to a young of P. armata or P. maculata.
Platythelphusa immaculata	up to 1.2 inches (3 cm)	The dorsal carapace is uniform grey-pink to orange-brown, lacking stains or spots. The tips of chelipeds and pereiopods are white.
Platythelphusa praelongata	up to 1.2 inches (3 cm)	The carapace is pink to grey-pink. The tips of chelipeds and pereiopods are white. The propodus and dactylus of chelipeds are red.

For all Tanganyika crab species, the carapace is subhexagonal, rounded, and wider than long.

Platythelphusa tuberculata and Platythelphusa praelongata (as deep lake dwelling species) have elongated slender legs which facilitate movement and tactile predation on mud.
Platythelphusa maculate has a very small and rounded body that is advantageous for living inside empty gastropod shells.
Platythelphusa conculcata and Platythelphusa immaculata have markedly flattened carapaces, it allows them to get into narrow crevices in rocky substrates.
The largest-bodied Tanganyika species, Platythelphusa armata has greatly enlarged claws to open the shells of heavily armored gastropods.

Lifespan of Tanganyika Crabs

The life span of these crabs is unknown. Currently, there is no data available on the maximum lifespan for different Platythelphusa species in the wild.

However, due to the fact that adult crabs do not molt for long periods of time (months), this suggests that in captivity they can live for several years (3 – 5 years on average).

Their lifespan will greatly depend on the conditions they are kept in, how well you feed them, and how stressful your aquarium environment is for them. Tanganyika crabs will live most in an aquarium containing low competition and the absence of various larger animals.

Typical Behavior of Tanganyika Crabs

Tanganyika crabs are fully aquatic animals. They require permanent bodies of water for survival since they live in open water.

Unlike many other crab species, these crabs are known to be non-burrowers. However, Tanganyika crabs may do some shallow burrowing (characterized by a simple tube-shaped burrow oriented horizontally) into debris and underside of rocks during periods of temperature extremes or when no other structural habitat is available.

Generally, they prefer to find shelter under rocks and logs.

Although Tanganyika crabs can tolerate high stocking densities better than most crab species, it does not mean that they are social. Their aggressiveness depends not only on individuals but mostly on species. The larger the crab species the more aggressive they can be.

Male-male antagonistic interactions appear to be the main problem in the tank. Therefore, it is recommended to keep one male and one or two females in the group.

Although these crabs are considered to be nocturnal due to their peak activity being after dusk, one of the best things about them is that Tanganyika crabs are not timid animals. On the contrary, they are pretty active and outgoing. In the absence of large or aggressive animals in the tank, you will often see them in the open.

Note: Nocturnal behavior is mostly dictated by the risk of being predated upon. This is instinctive behavior.

Tanganyika crabs are pretty messy and destructive. Be prepared that these crabs will redecorate your aquascape to their liking.

Features:

Social: No
Active: Yes
Peaceful: No
Burrowers: No

Diet of Tanganyika Crabs

The crabs of the genus Platythelphusa can be characterized as a scavenger that is opportunistically carnivorous. It means that they will eat just about any food they manage to find on the bottom of your tank.

In the wild, they consume algae (Oocystis sp. Ulothrix sp.), cyanobacteria (Anabaena sp. Chroococcus sp. Oscillatoria sp.), benthic diatoms (Encyonema sp., Rhopalodia sp., Nitzschia sp., Surirella sp.), plant litter (predominantly of bark and plant debris), detritus (including sand and silt), aquatic insects, gastropods, fish eggs, etc.

According to the study, gut contents revealed no apparent differences in the types of dietary constituents that were ingested between the species. Basically, it showed no clear evidence of specialization, except for Platythelphusa armata which consumes gastropods more frequently than other crab species of this genus.

In captivity, for the best growth, Tanganyika crabs need a good mix of meats and vegetation, where their feeds should contain protein at a level of about 20 – 30% of the diet.

When these crabs are kept as pets in aquariums, suggested foods for them are (some links to Amazon):

leaves,
plants,
vegetables,
crushed snails,
earthworms,
brine shrimp,
krill,
mysis,
dead fish or shrimp,
Artemia sp.
Shrimp pellets,
Shrimp Granules,
Shrimp food (Hikari’s crustacean food like Hikari Shrimp Cuisine),
Frozen blood worms, etc.

Features:

Diet Type: Omnivores / Carnivore.
Food Preference: Mix of meats and vegetation.
Feeding Frequency: 3 – 4 times a week for adults. Daily for juveniles.

Feeding Rules:

Leave their food for 12-24 hours before removing it. Leaves can be left for several days in the tank. Just make sure that whatever they do not consume in one day is removed to prevent water contamination.
Check the burrows. Keep in mind that crabs often drag and store food in their hiding spots for later consumption. Check them from time to time to prevent any bacterial contaminations.
Do not give them the same food all the time. Provide various food items to diversify the diet. It will make them stronger and grow faster.
Aggression. They become more aggressive when hungry. Keep in mind that protein plays a fundamental role in their life. If they do not get enough they also become aggressive and may even turn cannibalistic!

Do not forget that also calcium plays a huge role in crabs. Therefore, I highly recommend reading my article “How to Supplement Shrimp and Snails with Calcium”.

Are Tanganyika Crabs Plant Safe?

It depends on the species. Large crabs and plants are not compatible. They will eat, cut, and uproot just about any plant they can get their claws on. At the same time, small individuals should not harm your plants.

Nonetheless, if you are not sure what species you have, it will be better to play safe and use only:

plastic plants,
floating plants,
some cheap plants that you are ready to lose and replace.

Keeping and Caring for Tanganyika Crabs

Owning any pet carries significant responsibility and obligation to address its core needs! Here are some care guidelines to help you out:

Tank size:

Tanganyika crabs do not require a lot of space. For large species (such as Platythelphusa armata), a 10-gallon (40 liters) tank is enough to house 1 adult crab. For smaller species, it is possible to use even nano-tanks (5-gallon or 40 liters).

Important: Having a larger tank is always preferable for the stability of water chemistry. In addition, it can be easier to make diverse areas for them to hide.

Note: Like all crabs, they are known to be able to climb vertical surfaces. The good news though is that these crabs are completely aquatic. In the wild, they have never been observed out of the water and they die after a few hours in dry air. Therefore, they usually do not escape on purpose. Nonetheless, they can fall by accident, so, a tight-fitting lid is essential.

Water Parameters:

Tanganyika crabs are one of the few fully aquatic crab species, they have no need for land.

Water parameters will determine whether or not your experience in this hobby is a success. Rift Lake African crabs, that are from Lake Tanganyika, require different water parameters than the other freshwater crabs to thrive.

Temperature The ideal water temperature for keeping Tanganyika crabs is between the range of 77 – 81 °F (25 – 27 °C). You may have to use a water heater to keep the water temperature stable all the time.

Keep in mind that the water temperature will directly affect your crabs’ behavior patterns. The warm temperature will increase their metabolism and they will be much more active than if they were kept in cooler water temperatures.

pH: Maintain optimal pH values between 7.0 – 8.5 for the crabs to thrive in your freshwater aquarium. It is best to test the pH of your tank regularly

Hardness: They will appreciate optimal GH between 10 – 20 and carbonate hardness around 7 – 10 KH.

Ammonia and Nitrite: These compounds always should be at zero because they are extremely toxic.

Maintenance: Water hardness naturally drops over time because minerals do not stay suspended in water for a long time. Therefore, do 20 – 25 % water changes every week.

Filtration:

As long as you have got the filter that works great with the size of the tank you have got you will be fine but only if you keep small species.

Large Tanganyika crabs will definitely chip, chew and break apart the sponge over time. So, keep that in mind.

Lighting:

Tanganyika crabs are nocturnal animals and prefer subdued lighting. Basically, you can choose whatever lighting you like.

However, if you have plants, lighting should be adapted to their needs.

Substrate:

In their natural habitat, Tanganyika crabs are mostly found in all rocky littoral substrate types (such as cobbles, pebbles, and boulders) and are most often attributed to protection from predation.

In captivity, it will be better to have sand or gravel substrates. There is no need for a deep substrate. It can be 0.5 – 1 inches (1 – 2.5 cm) deep.

This way it will be easier to clean the substrate after feeding them. Remember, these crabs are messy. Over time, uneaten food will work its way into the substrate. Eventually, it will cause an ammonia spike. We do not want that.

Decorations and Hiding Places:

Decorations provide hiding places (shelter and protection) and minimize their stress. This is especially crucial for the molting process. Predation or even cannibalism after molting can become a big problem.

Tanganyika crabs will appreciate all types of leaves, rocks, driftwood, PVC pipes, plastic mesh, and other decorations to enrich the environment in your tank.

Related article:

Do We Need Tank Decoration? Simple Ideas

Tanganyika Crabs and Molting Cycle

The molting process (the molt cycle) is the process by which a crab grows. Because crabs have an exoskeleton, they must molt (shed the old exoskeleton) in order to grow. It also allows them to restore lost limbs.

This process consists of 4 phases:

pre-molt,
molt,
post-molt.
inter-molt.

For more information, read my article “Crabs and Molting Process”.

Important:

NEVER disturb your Tanganyika crabs when they are about to molt. Do not panic even if you have not seen your it for a few days in a row! Give it time. This is the most stressful moment in its life.
Keep putting and replacing food in the tank! You never know when they can come up from the molt.
Keep giving them calcium-rich food.
Also, do not remove the old exoskeleton from the tank. It contains lots of minerals and your Tanganyika crabs will eat it later.

Rules: How to Care and Handle Tanganyika Crabs:

Tanganyika crabs are not pets you can play with. Do not take them out just because you want to.
Tanganyika crabs should never be lifted up by their legs or claws! They can lose a limb by autotomy.
Do not leave uneaten food for too long. It can cause smell and bacteria in their enclosure. Remember, these crabs like to store uneaten food in their burrows.
Provide as many hiding places as you can.
Make sure the lid of the tank is closed tightly.

Related article:

How to Handle your Pet Crustaceans

Breeding Tanganyika Crabs

The reproductive traits of the genus Platythelphusa haven’t been fully described in the scientific literature (at least I could not find any at the moment of writing this guide). According to the scarce information:

Tanganyika crabs start breeding well once old enough and established in the tank.
Platythelphusa species are sexually dimorphic. Males have a narrow and slimmer plate while females have a broad plate on their belly to carry eggs and hatchlings.
They do not have free-swimming larval stages.
In contrast to marine crabs, Tanganyika crabs produce relatively small quantities of large eggs (20 – 50).
The eggs hatch inside the female brood pouch.
Hatchlings are fully formed miniature crabs.
Females protect baby crabs in the brood pouch for a few weeks, during which they undergo several molts until they are released.

Interesting fact: According to the study, Tanganyika endemic crabs are similarly prone to hybridization.

Tanganyika Crabs and Suitable Tankmates

Tanganyika crabs are relatively aggressive animals. Males are extremely likely to fight when housed together.

It is not recommended to keep them in a community tank with fish, freshwater snails, small frogs, crayfish, and other crab species. Some hobbyists managed to keep them with fast-swimming Tanganyika cichlid species. However, bottom-dwelling, slow-moving, or fish with long fins (like Betta) will be the first ones to get hurt.

Note: Platythelphusa armata (the largest species) is a specialist molluscivore, feeding on the extremely abundant snails. Their remarkably enlarged claws are advantageous in crushing the heavily calcified and exceptionally sculptured shells of gastropods.

Tanganyika crabs usually do not hunt for dwarf shrimp. Dwarf shrimp are too small and too fast for them. However, they are opportunistic and will eat whatever they catch. It means that you may still lose shrimp from time to time.

Related articles:

Aquarium Crabs and Tankmates. Possible or Not?

In Conclusion

Unfortunately, these freshwater crabs from Africa are not well documented, and only a few species have been the subject of studies to some degree.

All Tanganyika crabs need is a bit of background knowledge to recreate their ideal conditions and allow them to thrive in your home tank. Their habit of scavenging will keep the tank environment clean and healthy and save money on expensive foods.

References:

Sternberg, R. von, and N. Cumberlidge. “A cladistic analysis of Platythelphusa A. Milne-Edwards, 1887, from Lake Tanganyika, East Africa (Decapoda: Potamoidea: Platythelphusidae) with comments on the phylogenetic position of the group.” Journal of Natural History33, no. 4 (1999): 493-511.
Schram, Frederick, Saskia Marijnissen, Neil Cumberlidge, and Ellinor Michel. “Two new species of Platythelphusa A. Milne-Edwards, 1887 (Decapoda, Potamoidea, Platythelphusidae) and comments on the taxonomic position of P. denticulata Capart, 1952 from Lake Tanganyika, East Africa.” Crustaceana77, no. 5 (2004): 513-532.
Cumberlidge, N. “The African and Madagascan freshwater crabs in the Museum of Natural History, Vienna (Crustacea: Decapoda: Brachyura: Potamoidea).” Annalen des Naturhistorischen Museums in Wien. Serie B für Botanik und Zoologie(1997): 571-589.
Marijnissen, Saskia AE. “LAKE TANGANYIKA CRABS.”
Reed, Sadie K., and Neil Cumberlidge. “Taxonomy and biogeography of the freshwater crabs of Tanzania, East Africa.” (2006).
Cumberlidge, Neil. “The African and Madagascan Freshwater Crabs in the Museum of Natural History, Vienna.” (1997).
Marijnissen, S. A. E., E. Michel, M. Kamermans, K. Olaya-Bosch, and M. Kars. “Ecological correlates of species differences in the Lake Tanganyika crab.” (2008).
Capart, André. Crustacés décapodes, brachyures. Institut Royal des Sciences Naturelles de Belgique, 1951.