Red Claw Crab
Perisesarma bidens
A feisty brackish crab that needs salt and a land area to climb out onto.
| Difficulty | Beginner |
| Min. Tank Size | 40 L |
| Temperature | 24.0–28.0 °C |
| pH Range | 7.5–8.5 |
| Max Size | 10.0 cm |
| Lifespan | 2-4 years |
| Diet | Omnivore |
| Temperament | Semi-aggressive |
Overview
The Red Claw Crab (Perisesarma bidens) is a feisty brackish crab that needs salt and a land area to climb out onto. It reaches about 10 cm and can live for roughly 2-4 years with good care.
This guide covers everything in plain language: tank size and setup, water parameters, the best foods (with recommended brands), which shrimp and tank mates it can safely live with, breeding, and the common problems to avoid. It is rated Beginner to keep.
Natural Habitat & Origin
Crabs are crustaceans from rivers, mangroves and estuaries. Most are semi-terrestrial and need access to air and land, and many need brackish water, so they are usually kept in special paludarium setups rather than standard aquariums.
Tank Size & Setup
Provide at least 40 litres. Give it space, hides and a secure setup suited to its size and habits.
Most crabs need a land area to leave the water (floating platforms, cork bark, a sloped beach), a sealed lid, and for many species some marine salt to make brackish water.
Always add invertebrates only to a fully cycled, mature tank - they are far more sensitive to ammonia and nitrite than most fish.
Water Parameters
Keep the Red Claw Crab at 24-28 °C with a pH of 7.5-8.5, in moderately hard water (GH 8-15, brackish); they are happy in most Australian tap water once it is dechlorinated and stable.
Stability is everything for invertebrates: test regularly, keep ammonia and nitrite at zero and nitrate low, drip-acclimate new arrivals slowly over an hour, and make only small, steady water changes. Remember that copper - found in some fish medicines and plant fertilisers - is lethal, so always check labels.
Diet & Feeding
The Red Claw Crab is a omnivore. In Australia, good options include Hikari sinking pellets, Dymax dried foods, blanched vegetables and small protein treats, offered where the crab can reach them out of the water.
Feed lightly - invertebrates get much of their food from natural biofilm and algae, and overfeeding quickly fouls the water and triggers losses. A little, a few times a week, is plenty for most shrimp and snails.
Which Shrimp & Tank Mates Can Live Together?
Important: this crab is semi-terrestrial and is not a true fish-tank animal. It needs a land area to climb out onto (a paludarium setup), and most species need brackish (slightly salty) water. It can catch slow fish and shrimp, and is an expert escape artist, so a very secure, sealed lid is essential.
Breeding
Most aquarium crabs are hard to breed at home because their young need brackish or marine water to develop, so captive breeding is uncommon.
Common Problems & Care Tips
Moulting is the riskiest time - the animal hides, goes soft and is vulnerable, so never disturb a moulting crayfish or crab, leave the shed shell in the tank for it to eat (it restores calcium), and make sure it has calcium and iodine in the diet.
Quarantine and acclimate all new livestock carefully, and watch daily for sluggishness, failure to eat or trouble moulting.
Is the Red Claw Crab Right for You?
The Red Claw Crab suits beginners and experts alike, as long as you can provide 40+ litres, the right water, copper-free conditions and suitable tank mates.
Get the basics right and these fascinating invertebrates are some of the most rewarding animals in the hobby. Use our aquarium tools to plan your setup and browse our fish and plant guides for safe tank mates.