PTYCHOGNATHUS CARE GUIDE
Ptychognathus barbatus - Brackish pom pom crab Image Source: AquaticArts
Author: Albomita
Ptychognathus barbatus is a species of brackish-water filter-feeding crab that has been documented in regions such as southern Taiwan and New Caledonia. These crabs have distinctive tufts of hair on their claws, which they use to collect fine food particles from the water. In addition to filter feeding, they also scavenge using their claws. Despite being commonly sold as "freshwater pom pom crabs," this is incorrect P. barbatus does not live in freshwater. This widespread misinformation is often perpetuated by sellers within the exotic pet trade. In reality, they inhabit brackish coastal zones with tidal influence, and any freshwater setup is unsuitable for long-term health.
Common Names
Ptychognathus barbatus is also commonly known as:
Freshwater pom pom crab (misleading)
Pom pom crab
Brackish pom pom crab
Members of the species
Ptychognathus barbatus
Interesting Information
Ptychognathus barbatus is often mislabeled as a freshwater species.
Known for their hairy claws, which assist in filter feeding and food collection.
Not much detailed husbandry information exists in the hobby or literature.
Native to beaches and brackish river mouths where fresh and salt water mix.
Physical Characteristics
Size: Adult individuals typically reach a size of approximately 1 inch (2.5 cm) or less.
Appearance: They possess distinctive hairy patches on their claws, giving them a "pom-pom" appearance, which is the origin of their common name.
Life Span: Can live for decades if looked after correctly.
Conservation level
Unknown – There is limited data on wild populations, so sustainable and ethical sourcing is recommended. Supporting reputable sellers who follow responsible collection practices is important to minimise environmental impact.
Reputable sellers
AquaticArts (US ONLY)
Care Level
Dark Method: (UNKNOWN)
Love Method: Medium (as of 5/30/2025) – While relatively hardy, P. barbatus requires a brackish environment with stable salinity and temperature, making care more complex than fully freshwater species. Their filter-feeding nature also demands particulate-rich water and a mature tank.
The Dark vs Love Methods Explained
Enclosure and Environment
Ptychognathus barbatus is a brackish-water crab that lives in tidal environments. A setup mimicking these transitional ecosystems is essential.
Tank Size: 5 gallons for one; 10 gallons for a group of three
Salinity: 15–32 ppt salinity | 1.011–1.024 SG I would aim for something in the middle for the most success.
Temperature: 78–85°F (25.5–29.5°C)
Humidity: N/A
Filtration: Aquarium filtration is required, and something that provides a good amount of flow without blasting the crabs is advised.
Lighting: A natural day-night cycle is best, and any aquarium light will be enough to keep them happy.
Substrate
Any substrate is acceptable; they do not appear to have specific substrate preferences.
Cohabitation
Ptychognathus barbatus can cohabitate peacefully under proper conditions.
Best setup: Groups of three or more in 10+ gallons
Monitor for aggression, especially during molting periods.
Diet
These crabs are omnivorous with a strong filter-feeding component to their diet.
Primary Foods:
Particulates in the water (naturally occurring in mature tanks)
Biofilm
Blanched vegetables such as spinach
Fish foods
Shrimp (fresh or freeze-dried)
Providing a source of calcium, such as cuttlebone, can aid in exoskeleton development and molting processes.
Data Source
The information in this guide was kindly researched and provided by the team at Crustacean Council