Red Apple Crab (Metasesarma Aubryi)
A rather uncommon and unknown crab in the hobby, the Red Apple Crab is a beautiful and small species of land crab hailing from the lands of Sulawesi, Indonesia. As adults they are primarily and only freshwater, and will not need any salt in their intake or water. However, as babies, they hatch as nymphs, and need to be reared very much like Amano Shrimp nymphs. Another interesting part of these crabs is their ability to change the color of their shell from brown to orange, to even a bright red, depending on their mood, thus earning them the nickname "Red Chameleon Crab". Carapace diamater reaches from 3-5 centimeters.
Difficulty of keeping: 2/10 (Very easy)
Tank size: 60x40x40 cm can easily fit 8 crabs or more
pH: 7-8.5 is best in my experience
Temperature: 68-86 degrees Fahrenheit
Lifespan: Unknown as of 1/22/19
Metasesarma aubryi is a brightly colored crab. When the animals feel optimally in their skin, the base color is bright red, both on the back, legs and scissors. On the back there is a large black spot. The color can vary from this bright red to rust brown, with almost no drawing on the back. This has nothing to do with health but with state of mind and camouflage. In my experience, the bigger and more active individuals show the most color, and the ones that are near moult or are lesser stature tend to be more brown.
As mentioned earlier, they are found in Sulawesi, Indonesia, but can also be found in places like Malaysia and Thailand. They tend to stay close to freshwater streams inland and are found in forests near the coastline.
This species is fairly tolerant towards other species. As long as there are enough shelters, even several males tolerate each other perfectly. It is advisable to have at least as many females as males, preferably even more. It is also very much recommended to have as many as the aquarium/vivarium can carry, as they tend to explore more often and not stay in hides all day when they have numbers.
In males there is a V-shaped cover in what is used for sperm transfer during mating. The female has a round, wide valve under which the eggs are stored. This is almost as wide as the full belly shield.
This is a male's belly shield.
And this is a female's.
In the literature and on the internet it can often be read that these animals also like to climb. I never noticed much of it in my animals.They like to spend a lot of time in or near their regular shelter. With a muted lighting they will show some more activity.
Care in the Vivarium/Aquarium
It is best to have as many hiding spots and caves as possible, so that the crabs feel safe and secure, and thus, come out more often to feed and scavenge. Substrate should be of material that does not mold or rot too quickly, such as coconut fiber. It is also highly recommended to have good ventilation to reduce the amount of mold, though springtails are still highly recommended.
However, you can also make a complex setup with a complete substrate mix of 2 parts fern dust/fiber used for orchids, 1 part coco fiber/peat moss, 1 part charcoal or even activated carbon if that is cheaper than the former, 1 part sphagnum moss and 2 parts orchid bark, usually found in pet stores in big bags. Mix all these materials together and your substrate will not only last longer, but will harbor microfauna better for use in eating the inevitable fungus and mold, since this enclosure will need to stay at 70-85% humidity at all times. I highly suggest reading this instructional guide on how to setup your own vivarium, with just a few tweaks here and there later on in here. NEHERP - Vivarium Construction 101 - The most complete vivarium building articles online!
You can also use a shallow water bowl for the crabs' daily moistening of their modified gills, as these need to stay wet so they can breathe air. But, you can also make it better by making a clean spot in the enclosure where none of the substrate can get into, and make it into a small semi-aquarium, with a small Hang on Back filter as filtration. I used a Tupperware container and put substrate all around it, then put the HOB nearby to act as the filtration system.
Muted or weak lighting is recommended, as otherwise the animals will remain hidden for almost the entire day, unless there are quite a few crabs in the enclosure. I read online that they like to nibble on plants, but mine don't really do that, so make the enclosure a planted enclosure at your own discretion.
Lastly, a calcium block or cuttlebone in the enclosure would act great as a source of extra calcium for these animals, as this is crucial to a successful molting.
Metasesarma species tend to lean towards a more fruit and vegetable diet than their natural neighbors, the Vampire Crabs. In my experience, they love melon, apple, grapes, romaine lettuce, and mango. This can also be supplemented with fish meats of any variety, though I mostly treat them with chunks of salmon. They will also accept sinking wafers and Algae Wafers, so as long as they were left to soak in water for a minute or two. When you have living moss or dry leaves in the terrarium, the animals often find a lot of food in between. Oddly, if there are any weeds such as clover or dandelion in the enclosure, they'll happily eat that.
As of this writing, I am not sure if there are any viable tankmates for Metasesarma Aubryi other than themselves. Adults will mostly leave springtails alone, and younglings will benefit from them. Possibly, Vampire Crabs (Geosesarma Dennerle) is a good bet, as well as Batik Crabs (Metasesarma Obesum), but I will need too experiment in the future once I get a hold of these species.
I have not tried breeding these species yet, but once the female I have is of age, I will definitely try. I speculate that rearing the babies will very much be like raising Amano Shrimp nymphs, where they need to be raised in brackish water. More information will be added here once I have a successful breeding attempt.
Getting them to breed is easy, just so long as the crabs are well-fed, they will mate on land and you will soon see eggs under the female.
I am both looking forward to breeding these creatures, and quite horrified, as for anyone who tried breeding Amanos can attest. Hopefully, it will be a success!
All crustaceans, either mass-produced or wild-caught, have a chance of having shell rot, a disease gained from being burned with high dosages of ammonia to the point that the ammonia starts eating away at the shell of the animal. This can be remedied by providing foods with high calcium content and water free from ammonia. if cared for properly, their next moult will be free from most shell rot scars, and deeper wounds will slowly disappear with each molt.
Q: I found a shell of my crab, and it's hollow! Did it die?
A: Do not worry, this is what we call a molt. Almost all crustaceans go through a process that is known as molting, where the crustacean removes it's old shell to grow a new one, as this shell does not grow with them, leaving a carbon copy of themselves. So they need to perform this task periodically in order to gain some more size and weight.
You can discard this shell if you please, especially if it has shell rot, but you can also mash this shell with a mortar and pestle or blend it in with other foods to make a nutritious meal for them to regain lost calcium.
Q: My crab is missing a limb... What to do now?
A: Many crustaceans perform sparring matches with each other, and sometimes these matches result in losing a leg or claw. No worries, these will grow back next molt, so as long as there is ample food and calcium! A sign of the limb growing back is a thing called a Limb Bud growing where the lost limb once was. This bud will burst into a new leg once the crab completed a molt.
Q: My enclosure stinks... Why?
A: Many crustaceans are infamous food hoarders at times, and will tend to hide foods in their burrows or hides to rot. It is recommended to check each hide and burrow periodically, so that they are clean of spoiled food.
I hope you enjoyed reading this care information, this is my first time making a sheet here on Fishlore, and hopefully I will make more to come with some of my other freshwater land crabs!