Overview
The red claw crab is a small, lively crab with a dark shell and bright orange-red claws that make it easy to spot. It comes from coastal areas and mangroves in Asia, and here is the most important thing to know: it is not a fully aquatic animal. Red claw crabs need to be able to climb out of the water to breathe air and rest, so they must be kept in a paludarium, a tank that has both water and dry land, not a fully underwater aquarium.
They also do best in slightly salty (brackish) water, which matches the mangrove homes they come from. Red claw crabs are curious and active, but they are also bold and a little territorial, and they are known escape artists that will climb out of an open tank. With a secure setup that gives them land, brackish water, and hiding spots, they are fascinating to watch as they scuttle around and wave their bright claws.
| Care level | Moderate |
| Adult size | 2 in (5 cm) leg span |
| Lifespan | 2 to 3 years |
| Temperament | Bold and territorial |
| Min. tank | 10 gal (38 L) paludarium with land |
| Temperature | 75 to 82 F (24 to 28 C) |
| pH | 7.5 to 8.5 |
| Diet | Omnivore, scavenger |
| Social | Territorial, keep singly or with space and hiding spots |
What it is and where it comes from
The red claw crab is a small semi-terrestrial crab from mangroves and coastal areas in Asia. Semi-terrestrial means it spends part of its life out of the water. Its dark body and bright red claws make it striking, but its needs are different from a normal fish, since it must be able to leave the water.
Tank and water needs
Red claw crabs need a paludarium, a tank with both water and dry land they can climb onto, around 10 gallons (38 L) or more. They do best in brackish water (freshwater with a little marine salt added) kept at 75 to 82 F (24 to 28 C) with a higher pH of about 7.5 to 8.5. A tight lid is essential because they are excellent climbers and will escape a tank left open.
Diet and feeding
These crabs are omnivore scavengers that eat almost anything. Offer sinking pellets, algae wafers, blanched vegetables, dried leaves, and occasional protein like frozen foods. They will also pick at leftover food, helping clean up, but do not rely on scraps alone to feed them properly.
Tankmates and temperament
Red claw crabs are bold and a bit territorial, and they may pinch or catch slow fish and small shrimp. They are not the peaceful community animal some people expect. Give each crab its own space and hiding spots, keep only fast fish that stay in open water if any, and be aware they can squabble with each other.
Moulting
Like all crabs, the red claw crab moults, shedding its whole shell to grow a bigger one. Just after moulting its shell is soft and it is defenseless, so it hides until the new shell hardens. Leave the empty shell in the tank, since the crab may eat it to reclaim minerals.
Fun facts
- Red claw crabs are semi-terrestrial and must be able to climb out of the water.
- They do best in brackish (slightly salty) water like their mangrove homes.
- They need a paludarium with land, not a fully underwater tank.
- They are excellent climbers and escape artists, so a tight lid is a must.
- They moult to grow and hide while their new shell hardens.
Frequently asked questions
Can red claw crabs live fully underwater?
No. They need to climb out to breathe air and rest, so they must have land in their tank. A fully submerged aquarium is not suitable for them.
Do red claw crabs need salt in the water?
Yes, they do best in brackish water, which is freshwater with a little marine salt added, matching the mangroves they come from.
Are red claw crabs peaceful with fish?
Not really. They are bold and territorial and may pinch or catch slow fish and small shrimp, so they are not a safe community animal.
Why do I need a lid on the tank?
Red claw crabs are expert climbers and will escape any open tank. A tight-fitting lid keeps them safely inside.
