The Red Claw Crab (Perisesarma bidens) is an exceptionally charismatic and fascinating semi-aquatic crustacean known for its vibrant purple-to-brown body and striking, contrasting red claws. Highly active and full of personality, they provide an engaging display for hobbyists looking to venture beyond standard fully aquatic fish setups.

Note for Beginner Aquarists: Unlike typical freshwater crabs or shrimp, Perisesarma bidens is a semi-aquatic brackish species that requires a specialized paludarium layout (a hybrid habitat featuring both a land area and a shallow water section). Keeping them in a traditional, fully freshwater and submerged aquarium will lead to health decline.

Short Description & Highlights

Perisesarma bidens features a compact dark carapace coupled with eye-catching crimson claws that make it a standout addition. Reaching a modest span of about 3 to 4 inches, it spends a significant portion of its time exploring shorelines, climbing structures, and foraging on land. Beginners will find them hardy and rewarding if proper low-end brackish conditions and secure, escape-proof land platforms are provided.

Key Product Highlights:

Detailed Beginner Care Guide

1. Habitat Setup (The Paludarium)

To thrive, these crabs require an enclosure with roughly 60% to 70% dry land and 30% shallow brackish water (or at a minimum a balanced 50/50 split). Use aquarium-safe marine salt mix to achieve a low-end brackish specific gravity. Because they are legendary escape artists, a tight-fitting aquarium lid or cover is strictly required to prevent them from scaling filter tubes or glass corners.

2. Diet & Nutrition

Red claw crabs are opportunistic omnivores and scavengers. Their diet should consist of sinking shrimp pellets, algae wafers, bloodworms, and blanched vegetables (such as zucchini or spinach). Crucially, they require a supplemental source of calcium—such as a piece of cuttlebone placed on the land area—to ensure they can successfully harden their shells following the moulting process.

3. Behavior & Tank Mates

These creatures are primarily nocturnal, spending daylight hours hidden inside cave structures, driftwood crevices, or burrows before becoming active at night. Due to their predatory nature and brackish requirements, they are best housed alone, in pairs, or in small groups with ample territory. They are generally incompatible with fully aquatic community fish or delicate live aquarium plants, which they will readily clip uproot, or consume.