Red claw crabs are very interesting to keep and a very easy impulse buy, but unfortunately there is still a lot of misinformation about their care to be found in aquarium stores and on the Internet. They are often kept in freshwater community aquariums, but their ideal habitat is actually a single species low-end brackish paludarium! Keep reading for more information about keeping red claw crabs and setting up a suitable home for them.
|Tank size||15 gal (54L) paludarium|
Perisesarma bidens, red claw crab, red clawed crab, mini crab. They’re also sometimes still referred to as Sesarma bidens.
Red claw crabs are naturally found in mangrove swamps in Asia. In these estuaries, rivers flow into the sea, creating a mix of fresh and salt water. The water is quite shallow, temperatures are tropical and the ground is usually covered with fine sand. This gives us some great guidelines for what a red claw crab paludarium should look like!
With a size of no more than around 4 inches (10cm), red claw crabs stay smaller than some of the other crab species available in aquarium stores, which is why they’re sometimes referred to as “mini crab”. Males are easy to tell apart from females: their characteristic red claws will be larger and the underside of their shell is pointy instead of broad and round.
As mentioned before, red claw crabs are not fully aquatic and should ideally be housed in at least a 15 gallon (54L) paludarium with plenty of access to land. They are also not freshwater crabs: water salinity should actually be around 1.005. As with all types of tropical aquarium setups, the water should be heated, filtered and cycled and a water change should be done regularly. For more information about setting up a brackish aquarium or paludarium (which is actually not as difficult as it sounds), check out this post.
Mimicking the natural habitat of your red claw crabs is quite easy and results in a very beachy looking paludarium. The land area should be sandy. Multiple hiding places are a must, because crabs need a quiet place when they are molting and vulnerable. For a realistic effect, you can add rocks, aquarium plants such as Java fern that can withstand brackish water and mangrove ornaments – real mangrove is possible too, but it’s not the easiest plant to grow and it gets very large.
Important! Red claw crabs are the ultimate aquarium escape artists. When setting up their tank, seal off any and all possible escape routes or you will find your crabs on your floor sooner or later. They dehydrate very quickly, so this can potentially be fatal. The water line should never be up to the rim of the tank, keep openings for filter/heater cords as small as possible and avoid placing decorations in a way that allows the crabs to climb all the way to the top of the tank.
When choosing red claw crabs it’s very important to try to avoid getting multiple males, as territorial fights are not uncommon and can sometimes result in injury or death. In a 15 gallon (54L) paludarium, 1 male and 2 females or 3 females would be a good place to start. It’s easiest to keep your red claw crabs in a single species setup, but if your water area is large enough it is possible to keep additional tankmates. When choosing, keep in mind that crabs do hunt fish, especially when they’re slow or sick. Tankmates that can withstand low-end brackish water and aren’t bottom dwellers, such as mollies, should work well.
Although red claw crabs do actively hunt, they are not carnivores. A healthy red claw crab diet should include plenty of proteins such as bloodworms and small pieces of uncooked fish or prawn. This should be supplemented with veggies like leafy greens, peas and spinach. Red claw crabs will usually also eat regular fish food, algae pellets and commercial crab foods like Hikari crab cuisine, which is a good way to help supply them with enough calcium to grow and molt succesfully.
Although they do spend a portion of their time hiding, especially when molting or scared, these crabs are very fun to watch and super interesting to keep once they come out. If you use a soil substrate, you’ll see your crabs displaying their natural scavenging behavior for most of the day. When they encounter another crab or a fish they will usually get defensive, raising their claws and chasing the intruder away.
Some aquarists report their crabs getting used to them and losing their fear after a while. However, if you ever have to handle your red claw crab for any reason don’t forget that they will still pinch hard enough to startle you!
Breeding red claw crabs is unfortunately very challenging and virtually impossible to do at home. Similar to some other invertebrate species like Amano shrimp, red claw crabs start their lives as larvae and will likely not survive in your aquarium. Females will often carry eggs, but these don’t hatch or the young die off almost instantly.
We kept red claw crabs in our tropical community aquarium for a while back when I was still clueless about fishkeeping and I had no idea how to properly house them. They unfortunately died quite soon, but it was long enough to find out they are super fun to keep! I’d definitely consider setting up a single species tank again in the future and I would recommend anyone to do the same. Just be sure to go for that brackish paludarium, as they really do seem to suffer without access to land.
If you have any more questions about keeping red claw crabs or if you want to share your own experiences, be sure to leave a comment below. Happy fishkeeping!
Cover photo: meanandpinchy