Freshwater Crab 5cm

Freshwater Crab

Australia is home to some incredibly unusual freshwater animals, and freshwater crabs are easily among the most overlooked. While they aren’t as commonly kept as shrimp or crayfish, species like Austrothelphusa agassizii offer fascinating behaviour, surprising intelligence, and a completely different style of aquarium keeping. For aquarists looking for something truly unique, these crabs are a fantastic alternative.

The Australian Freshwater Crab displays a broad, rounded carapace that ranges from earthy brown through to deep olive-green, allowing it to blend perfectly among rocks, timber, and leaf litter. Depending on the individual and locality, subtle orange or reddish highlights may develop around the claws and joints, particularly after moulting. Their large claws are constantly used for climbing, digging, and manipulating food, while the independently moving eyes give them an inquisitive personality that is endlessly entertaining to watch. Given plenty of structure, these crabs spend much of the day exploring every corner of the aquarium.

Sexing mature crabs is relatively straightforward by examining the abdominal flap underneath the body, with females displaying a much broader flap for carrying eggs. Breeding in captivity is uncommon, although females carry fertilised eggs beneath the abdomen until fully developed juvenile crabs emerge.

Tank Recommendations for your Australian Freshwater Crab

A minimum aquarium size of 60 litres is recommended for a single specimen, with larger aquariums required when housing multiple crabs. Provide plenty of rockwork, driftwood, and hiding places to establish territories, along with a secure lid, as freshwater crabs are excellent climbers and opportunistic escape artists. Stable water quality and good filtration are essential, while areas of both open substrate and cover allow them to display natural behaviours.

Suitable Tank Buddies

Freshwater Crabs are best considered opportunistic omnivores rather than true community animals.

Usually Compatible

Larger rainbowfish, silver perch, peaceful gudgeons, and other medium-sized fish that occupy the upper water column are unlikely to interact with the crab.

Sometimes Compatible

Larger catfish, Australian native fish, and robust bottom dwellers may coexist successfully in spacious aquariums with plenty of hiding places.

Rarely Compatible

Shrimp, snails, nano fish, and slow-moving bottom dwellers should generally be avoided, as the crab may attempt to catch them, particularly overnight or during moulting periods.

Feeding your Australian Freshwater Crab

Australian Freshwater Crabs are opportunistic feeders that readily accept a wide range of foods. The ideal diet would consist of quality sinking crustacean pellets supplemented with algae wafers, vegetables, frozen prawns, mussels, bloodworms, and other meaty foods to support healthy moulting and shell development.