The Pom Pom Crab (Ptychognathus barbatus) is a captivating freshwater crab species renowned for its unique “pom-pom” appendages, which resemble fluffy tufts of algae or tiny anemones on their claws. These peaceful, diminutive crustaceans are excellent for nano or planted aquariums, where they contribute to algae control and scavenging. With their endearing appearance and low-maintenance requirements, Pom Pom Crabs are a fascinating addition for aquarists seeking something different and engaging.

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Care Guide:

Scientific Name: Ptychognathus barbatus
Common Name: Pom Pom Crab
Family: Varunidae
Origin: Southeast Asia, including Thailand, Malaysia, and Indonesia, often found in slow-moving rivers, streams, and ponds.

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1. Water Parameters:

• Temperature: 72°F to 78°F (22°C to 26°C)
• pH Range: 6.5 to 7.5
• Water Hardness: Soft to moderately hard (3-12 dGH)
• Water Quality: Requires clean, well-oxygenated water with stable parameters.

Tip: Use a sponge filter or other gentle filtration methods to prevent strong currents, as these crabs prefer calm water.

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2. Tank Setup:

• Minimum Tank Size: 5 gallons for a single crab, with additional space for multiple crabs.
• Substrate: Fine sand or smooth gravel to accommodate their burrowing and foraging behaviors.
• Decor: Provide plenty of hiding spots using driftwood, rocks, and caves.
• Plants: Live plants like Java Fern, Anubias, and mosses create a natural environment. Floating plants can offer shaded areas.
• Lighting: Moderate lighting to support plant growth and mimic their natural habitat.

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3. Feeding:

Pom Pom Crabs are omnivorous scavengers that enjoy a varied diet.

• Primary Diet: Algae and biofilm found naturally in the tank.
• Supplementary Foods: Sinking pellets, algae wafers, and blanched vegetables (e.g., zucchini, spinach).
• Occasional Treats: Protein-rich foods like freeze-dried or frozen bloodworms, brine shrimp, or daphnia.
• Feeding Schedule: Feed small amounts 2-3 times a week, as they are efficient scavengers and will forage for leftovers.

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4. Tank Mates:

Pom Pom Crabs are peaceful and generally compatible with other small, non-aggressive species.

• Compatible Tank Mates: Nano fish like rasboras, small tetras, or guppies. Shrimp (e.g., Amano or Cherry Shrimp) can also coexist well.
• Tank Mate Cautions: Avoid housing them with aggressive or large fish that may prey on the crabs.

Note: Pom Pom Crabs may attempt to nip at very slow-moving or long-finned fish, though this is rare.

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5. Behavior and Temperament:

• Activity Level: Active and entertaining, often seen foraging and waving their “pom-poms.”
• Social Behavior: They are social but may display mild territoriality. Best kept singly or in small groups with ample hiding spots.
• Special Notes: They are mostly nocturnal but can be observed during the day in well-established tanks with secure hiding areas.

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6. Health and Maintenance:

Pom Pom Crabs are hardy but require stable, clean water conditions.

• Maintenance Tips: Regular water changes (10-20% weekly) and substrate cleaning are crucial to prevent ammonia spikes.
• Molting: Crabs molt as they grow, and they are vulnerable during this process. Provide plenty of hiding spots and avoid disturbing them while molting.
• Common Health Issues: Poor water quality can lead to stress and illness. Monitor for signs of inactivity or discoloration.

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7. Breeding:

Breeding Ptychognathus barbatus in captivity is challenging.

• Reproductive Behavior: Females carry eggs under their abdomen, but larvae typically require brackish water to develop, making breeding difficult in freshwater tanks.
• Breeding Setup: If attempting breeding, provide brackish water and research specific salinity requirements for larval development.

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Key Care Tips:

1. Maintain clean, stable water parameters with low flow.
2. Provide a well-decorated tank with hiding spots and live plants.
3. Offer a varied diet that includes both plant-based and protein-rich foods.
4. Monitor for molting and ensure a stress-free environment during this process.
5. Avoid aggressive tank mates and ensure they are not outcompeted for food.

With their whimsical appearance and engaging behaviors, Pom Pom Crabs make an excellent addition to planted or nano aquariums. Easy to care for and endlessly fascinating to watch, they are sure to become a favorite in any aquatic setup!