Sulawesi/Matano Crab Care Guide - REVISED & UPDATED EDITION

Prelude 

I published the first edition of this care guide in July of 2020 under the title, "My Experiences with Sulawesi/Matano Crabs," and dove into everything I knew and learned through my then year and a half of experience with the four species originating from the Malili Lake System of Sulawesi, Indonesia. Half a year on, I have kept each species in my care for three months minimum, and have learned even more valuable information about the proper husbandry of these crabs. This guide is meant to help potential keepers of Sulawesi crabs learn the care for these rare animals, which have very little literature about their husbandry in captivity. I hope this guide is serviceable to you, and if you ever have additional questions, or would simply like to discuss these amazing animals with me, I am always available. I can be found on email at liamhopkins39@gmail.com, or on instagram, @colorado_crustaceans. On instagram I post consistent content featuring these crabs. 

This guide will likely experience many revisions as I learn more, but for now, here is all I know.

Enjoy

Sulawesi/Matano Crab Care Guide - Revision 1.0 

Introduction

The ancient lakes of Sulawesi are home to dozens of unique, interesting, and beautiful invertebrates. The shrimp hailing from the lakes of Sulawesi are popular in aquariums, as are the native snails, commonly sold as rabbit snails. However, these invert-rich lakes are also home to five extremely special crab species. Four are currently available in the aquarium hobby, and those are the four I will be covering in this guide. The fifth species is yet to be imported to North America to my knowledge. 

Caridina Woltereckae, from Lake Towuti, Sulawesi

The Malili Lake System has three major lakes, Lake Matano, Lake Mahalona, and Lake Towuti. Towuti is the largest, while Matano is the deepest. All three are connected by rivers. Unfortunately, the lakes are being rapidly destroyed by numerous factors, and all crustacean life hailing from the lakes are considered endangered. Pollution from nickel mining on the shores of the lakes, soil erosion caused by human development, hazardous construction of hydroelectric dams, and the introduction of invasive flowerhorn cichlids have all caused the numbers of inverts in the lakes to drastically decrease in recent years. IUCN and top scientists that have studied the area have actually recommended the collection of species from the lake to be bred in home aquariums, and to thus save the species from complete extinction. I have bred the harlequin Sulawesi shrimp in my tanks (pictured above), and I am hoping to breed the various crab species, but have had no success...yet. 

Map of the Malili Lake System

The four crabs hailing from the lake are as follows, Syntripsa matannensis (purple Matano crab), Syntripsa flavichela (white claw Sulawesi crab), Parathelphusa ferruginea (gold leg Towuti/Sulawesi crab), and the most famous Parathelphusa pantherina (panther crab). The two crabs from the genus Syntripsa used to be in Parathelphusa, until a re-classification moved them to their own genus in 2006. 

I've been lucky enough to keep all four species in my home aquariums before. I've had one panther, two gold leg Towuti (althought I thought my first was a S. matannensis, I'll explain below), two purple Matano, and four white claw Sulawesi. 

But enough about me, let's talk about what these crabs truly need to thrive. Fortunately they are all very similar in care, but each crab has their own special knacks. 

Just like the shrimp that come from Sulawesi, the crabs do not tolerate a wide range of water parameters. This is arguably the most important aspect of their care. Temperature and pH are the most important for them. A pH any lower than 7.5 or above 8.8 will cause loss of color, sluggishness, and eventually issues molting, which will cause death. I keep mine at 8.4, which seems to be the pH that gets the most behavior out of them. For this higher pH, I use Salty Shrimp Sulawesi remineralizer, but Seachem's Malawi-Victoria Buffer also works just fine. I prefer Salty Shrimp only because it has added minerals that help molting. 

Temperature is a little more flexible, but shouldn't dip below 75, or over 88. The lakes are usually around 85, with the temperature varying a degree or two either way as the seasons change. I keep my tanks at 84 degrees. 

Beyond parameters however, these crabs are fairly simple. They are all strictly nocturnal, and dig burrows, though to variable degrees, which I will explain in detail for each species. To mimic their natural habitat, varying sizes of lava rock and driftwood are perfect. The love to dig burrows under large rocks and wood, and will move smaller rocks around their tanks to fit their liking. I mix sand with small pieces of lava rock for substrate, and they seem to love this.

Lake Matano 

Image Credit-Chris Lukhaup

In the evenings before big snow storms ( I am based in Colorado), all Sulawesi crabs get frantic and dig burrows, along with gathering food. This behavior may be in preparation for the monsoon rain season they experience in their native Indonesia, but regardless it is fascinating. My own research along with things I have read lead me to believe they can sense changes in barometric pressure through their antenna. 

All crabs can fit in pairs in a 20-gallon tank. Never keep two males of any species together unless the tank is minimum 35-gallon, with plenty of hiding spots. They will fight and rip each other apart. Males are much more gentle to females, though. Pairs have been the most successful for me.

They are not picky eaters. They eat essentially anything you feed them, but their favorites include Hikari crab cuisine, algae wafers, and mysis shrimp. In the wild, these crabs are specialized snail eaters, and will devour pest snails at an astonishing rate. I supplement mine with ramshorn snails I raise in other tanks. Just make sure any food you feed does not have copper or copper sulfate in it, copper is poisonous to all invertebrates, including crabs. 

These crabs are also extremely adept climbers. I lost both my second gold leg Towuti and panther to them escaping my tank up the heater. Escape-proofing your tank is absolutely essential. If you have even the tiniest doubt your tank isn't 100% secure, act on that fear. They will find a way to escape. Try to keep heaters and airstones as far off the bottom of the tank as you can. I also cover any holes in the tank lid with a towel weighed down by rock, and this works well. 

All crustaceans must molt, or shed their shells in order to grow. Juveniles molt often, while adults only once or twice a year. When Sulawesi crabs prepare to molt, they dig deep burrows and won't be seen for a week or so. This is normal. Do not disturb them if they have dug a burrow and aren't coming out. They wont eat during this period, either. To help in the molting process, a piece of cuttlebone can be added to the tank to add calcium to the water column. Calcium is a key component of crustacean development, and a deficiency in calcium could cause molting failures. Not just for Sulawesi crabs, but all crustaceans in home aquariums.

There are no confirmed reports of any of the Sulawesi crabs being bred in captivity. Through three years of searching online forums, I have only found one confirmed report of mating in aquariums. A man in Italy had panther crabs breed in his aquarium, but eggs never materialized. 

This lack of breeding information could be due to these species being impossible to raise in aquariums, due to factors like seasonal breeding, or certain changes in environment, like the rainy or dry season. Or, it's possible they have never been raised in captivity simply because no one has kept them long enough, or in the proper conditions to promote breeding. Regardless, it doesn't hurt to try, which is exactly what I, along with Jacob Green, who shared information and helped revise this, are doing currently. 

Individual Species

Nautilothelphusa Zimmeri

Lakes: Matano, Mahalona, Towuti

Size: Couldn't find any reliable reports on their size

As mentioned above, there is a fifth species of Sulawesi crab not sold in the aquarium trade. That is Nautilothelphusa Zimmeri. There is barely any information on these crabs anywhere, so I have no comments on them.

Image Credit-Chris Lukhaup

Purple Matano/Mulloscivore Crab

Syntripsa Matannensis

Lakes: Matano

Size: 3 inches across the carapace

In my opinion, the most beautiful crab from the Malili Lake System, these crabs possess a dark purple, sometimes almost red hue, and extremely interesting and powerful claws. They use this enlarged left claw 

and the large white teeth to crush open snail shells. These large crusher claws get them the name of their genus, Syntripsa. Syntrips was a Greek Mythology character who destroyed pottery with his large hands, just like these crabs destroy snail shells.

In my experience, these crabs are the most prolific snail hunters, but eat everything I feed. They are big eaters. 

Currently I have a mature male/female pair, who are not afraid of me at all unless I make sudden movements. I think this goes for all Sulawesi crabs, but keeping them in pairs brings out more activity and more interesting behavior. 

These crabs are also extensive burrowers. When my female molted, she and the male shared a cave for a few weeks, and since, they both have dug countless burrows. Their favorite places to dig are under large pieces of wood or rock. This species digs the largest and most complex of the burrows, being at least two inches deep, and in my largest example, almost eight inches wide under a piece of wood. 

I keep these crabs in pairs, and witness occasional slight aggression, like the male chasing the female away from food, but never anything violent. However, two males would not be able to co-exist. They are highly competitive over mates. I am hoping to breed this species, and if I do, I will release their own paper on the breeding cycle and their behavior. 

This species could probably be kept with fast, top water fish. Any other inverts must be avoided, as they will almost certainly end up being eaten. 

This species is the least tolerable to pH change. Large water changes should be avoided, and a good heater and pH regulator are a must.

My beautiful male S. matannensis

White Claw Sulawesi Crab

Syntripsa Flavichela

Lakes: Maholona and Towuti

Size: 2.5 inches across the carapace

The first specimen from this species I kept only lasted four days in my care before succumbing to a fungal infection the poor guy was shipped to me with. Fortunately, I was able to find more in the fall of 2020, and snapped up a trio. A very large female, and two very small specimens, one male and one female. Similar to the purple Matano above, these crabs are much more active in groups, but also, only one male can be kept per tank. They are the smallest Sulawesi crab, and also the hardest to find in my experience. They also have a larger left claw for smashing snail shells, but their's is much smaller than S. matannensis. These crabs are found in the lakes of Mahalona and Towuti, along with the river that connects the two lakes. Because this species can come from two different habitats, lakes or the river, their individual behavior varies between specimen. River based crabs are more active, and can be seen clinging to rocks or wood. Lake based are more shy, and dig burrows under large rocks. The difference between the two is minimal, but for this species, an airstone with good water circulation would be a good idea, to mimic the flow of a river. 

This species can be kept with fast moving fish, but any inverts should be avoided.

They are more tolerable to lower temperatures, I haven't tried adjusting their pH, so I am not certain how tolerable they are to pH swings. Regardless, don't tempt fate, and keep a stable pH around 8.4. 

Syntripsa flavichela is the smallest Sulawesi crab

Gold Leg Towuti/Sulawesi Crab

Parathelphusa Ferruginea

Lakes: Mahalona and Towuti

Size: 3 inches across the carapace

The gold leg Towuti crab gets its name from its beautifully colored legs. Shocker, I know. But, these crabs can actually have legs that are purple or even red. Gold is most common, but certainly localities of this crab in Lake Mahalona have purple legs. Judging off leg color is unreliable when identifying what species you have, the shape and large teeth (or lack thereof) on the left claw is the most reliable. The crab pictured 

to the left is a P. ferruginea with purple legs. He was sold to me as a S. matannesis, and I believed he was just that until just a few weeks ago. The way to tell the difference between the two species is the left claw. P. ferruginea will not have the large white teeth on the left hand. My first experience with this species was my first with any Sulawesi crab. My first specimen was super shy, I saw him out of his burrow maybe five times in the few months I had him. My second one, a true golden leg, was also kept in solitude, and was much more vivacious. Huge eater, always active every evening, and an amazing climber. The last detail was especially true, considering I lost him after he climbed up his heater and out of the tank. It may be that different colored legs, and therefore different localities, cause different behaviors. The purple leg was extremely shy, while my gold leg specimen was not in the slightest. Or maybe I just had two crabs with different personalities. This crab does burrow, but it seems the crabs in the genus Parathelphusa are less interested in burrowing, as both this species and the panther crab don't dig large burrows, unlike Syntripsa. They are big eaters, and go through snails quite fast as well. I have never kept this species in pairs, only in solitude twice. Once I have a free tank and find a male/female pair for sale, I will absolutely get them. They are tied for my favorite species with S. matannensis. This species grows large and is absolutely beautiful.

I would heed caution keeping this species with any fish, they are extremely fast moving and could probably catch most fish. All inverts should be avoided. I kept two killifish with the one pictured below, and he eventually caught and ate both. 

I lost my first species after a drop in Ph to 7.4, so they are quite sensitive. If you keep parameters in check, though, this species will be a favorite. Beautiful coloration, and very personable. 

My true gold leg. The most personable crab I've kept

Panther Crab

Parathelphusa Pantherina

Lakes: Matano

Size: 3.5 inches across the carapace

The most common, easiest to keep, and most vivacious of the Sulawesi crabs is the panther. Most people in the freshwater invert hobby are familiar with these crabs, as they are undoubtedly the most easily found of the Sulawesi crabs. They are the largest and most active species, but also the most aggressive. They are most prone to escaping, as well. I lost my only panther crab to him escaping. This species also has a huge appetite, eating whatever they can catch. Males from this species do not hide very much, and aren't easily startled like the other Sulawesi crabs. They are highly aggressive. I kept mine alone, but my friend Mirko Spalla kept them in a large colony and confirmed my suspicions that males of this species will kill each other. He also advised me that even male/female pairs can be potentially deadly. They hardly dig burrows, and are amazing climbers.

This species should be kept in solitude. It will eat fish or any inverts, and will likely kill others of its own species

They are unquestionably the least vulnerable to parameter changes, and have been reported to do just fine in pH as low as 7.0, and temps as low as 72. However, again, I wouldn't risk it, and keep them at 8.0, and 82 degrees. 

* There is a crab marketed as the "albino" or "oriental" panther crab. It is not P. pantherina, but rather Heterochelamon tessellatum, from south China. They are easily distinguishable, H. tessellatum is all white, P. pantherina is yellow-orange.

The panther crab is large and aggressive

Do not confuse the albino panther crab with P. pantherina

Thank you so much for reading my guide! I hope this guide helps you keep these amazing animals in your own tanks, and if you chose to, I wish you success and prosperity! I will update the success of my breeding projects on instagram, @colorado_crustaceans, if you wish to follow them. I am always willing to answer questions and discuss these animals, so do not be afraid to reach out! 

Special thanks to-

Jacob Green

Paulo Padilla

Mirko Spalla

Chris Lukhaup

Drew VanDyke

"Thank you for reading!"