Many crayfish species of the genus Cherax, have been exploited for ornamental purposes in recent years and Cherax boesemani is one of them. This species (commonly known as “Blue Moon crayfish” or “Rainbow Crayfish”) is absolutely gorgeous and beautiful. These crayfish are sure to attract attention in any home aquarium.
Although Cherax boesemani is not very common in the aquarium trade*, these crayfish can be easily recommended even for beginners. They are hardy and are easy to care for. In addition, they can breed in captivity! Cherax boesemani is one of the most underrated crayfish in the aquarium hobby.
Note: Cherax boesemani is generally available in Europe and rarely in the United States.
This care guide will give a special look into this remarkable species. This article covers all aspects, from natural habitat conditions and how Cherax boesemani should be cared for within your freshwater tank, to dietary requirements, behavior, etc.
|Warning: Make sure Cherax boesemani is not banned in your state and you do not buy or sell it illegally. For example. According to Florida Fish and Wildlife Conservation Commission (FFWCC 2017): This species is not allowed to be personally possessed, ported, purchased, sold, propagated, transported or used for commercial activities.
These crayfish are considered by the commission to have a high risk of becoming an invasive species.
Even if Cherax boesemani is not banned in your state or country, NEVER release them into the wild!
Quick Notes about Cherax Boesemani
|Name||Blue Moon crayfish|
|Scientific Name||Cherax boesemani|
|Other names||Cherax Blue Moon, Blue Papuan crayfish, Rainbow crayfish, Supernova crayfish, Blue Marble crayfish|
|Tank size (optimal)||20 gallons (~80 liters)|
|Size||up to 5 – 6 inches (12 – 15 cm) long|
|Optimal Temperature||75 – 88 °F (24 – 31°C)|
|Optimal PH||7.0 – 8.0|
|Optimal GH||3 – 25|
|Diet||Omnivore / Carnivore (as juveniles)
Omnivore / Herbivore (as adults)
|Life span||up to 5 years|
|Color Form||Beige, olivaceous brown, olivaceous green, reddish-brown, purplish, grey bluish, red to black with pinkish margins|
Etymology of Cherax Boesemani
Cherax boesemani was named after Dr.Marinus Boeseman, honoring him for his contributions to the scientific knowledge of freshwater crayfish of the genus Cherax in Irian Jaya (West New Guinea), Indonesia, and as the first collector of this species in 1955.
The generic name Cherax is thought to be a misspelling of the Greek word ‘charax’, meaning a pointed stake, or a thing that scratches.
The common trade names of this species are related to their color pattern.
Habitatof Cherax Boesemani
These crayfish live in shallow areas (rarely more than 10 fit or 3 meters) of the lakes with a lot of plants, wetlands, and tributaries of the lakes. These lakes have hard, mineral-rich water with neutral pH.
Description of Cherax Boesemani
Cherax boesemani is a relatively large crayfish. Generally, they only grow up to 5 – 6 inches (12 – 15 centimeters) in length. However, there are reports that some individuals can measure up to 10 inches (25 cm)!
This species can have several color morphs such as orange, red, beige, and greenish-gray, but the most common are blue or dark red to brown. These coloration morphs are usually exploited as ornamentals.
Their claws can also vary in color: beige, olivaceous brown, olivaceous green, reddish-brown, purplish, grey bluish, red to black with pinkish margins, and black tips. The uncalcified part of the claws is yellowish or pale to white. The claws do not have dimorphism and are equal in form and size.
Other than the very distinctive and different color pattern and size, Cherax boesemani is morphologically very similar to Cherax pulcher.
Lifespan of CheraxBoesemani
Currently, there is no data available on the maximum lifespan for Cherax boesemani in the wild.
However, in captivity, these crayfish can live up to 4 – 5 years, if appropriately cared for.
Typical Behavior of CheraxBoesemani
Cherax boesemani has a very complex social behavior. On the one hand, this is a solitary and territorial species, they are not social. On the other hand, they can be often found in close proximity to each other.
Anyway, it will be better to say that their aggression level is very low, compared to many other popular ornamentals crayfish species such as Blue crayfish, Red crayfish, Marbled crayfish, Cherax Destructor, etc.).
Unfortunately, when aggression occurs it happens rapidly. Cherax boesemani engages in chelae displays to indicate dominance prior to engaging in violent contact. Males are more aggressive and will likely attack other tank mates.
In spite of their size, these crayfish are very skittish and shy animals. They do not like staying in the open. The pick of their activity starts at dusk and gradually stops during the night, before sunrise, they are nocturnal. Therefore, do not expect to see them all the time in the display tank.
Cherax boesemani are not natural diggers. However, they can burrow in soft substrate.
They are also very good escape artists. It is good to have your tanks covered as much as you can.
- Social: No
- Active: No
- Peaceful: No
Diet of Cherax Boesemani
According to the study, Cherax boesemani is an opportunistic omnivore that can feed on a variety of food items. In the wild, they consume snails, insects, fish eggs, small fishes, veggies, aquatic plants, algae, and detritus.
In captivity, they need a good mix of meats and vegetation, where their feeds should contain protein at a level of about 15 – 20% of the diet.
Important: Adult animals are more herbivorous, whereas juveniles tended to be more carnivorous. Juveniles rely on protein for their rapid growth, they can even become cannibalistic when there is not enough protein food.
Suggested foods for Cherax boesemani include (some links to Amazon):
- blanched vegetables (broccoli, cabbages, carrots, cucumbers, lettuce, corn, spinach, peas, squash, leafy greens, etc.).
- crushed snails,
- tubifex worms,
- brine shrimp,
- dead fish or shrimp,
- Frozen bloodworms, etc.
- Shrimp food (Shrimp pellets, Shrimp Granules, Hikari’s crustacean food like Hikari Shrimp Cuisine, etc.),
- Diet Type:
- Food Preference: Mix of meats and vegetation.
- Feeding Frequency: 3 – 4 times a week.
Rules of Diet in Captivity for Cherax Boesemani
- Schedule. Feed them before lights out.
- Leave their food for 24 hours before removing it. To prevent water contamination, leftover feed should be removed by siphoning before fresh food was added. Leaves can be left for several days in the tank.
- Leave old exoskeletons. Do not remove molted exoskeletons to improve health.
- Check their hiding places. Keep in mind that Cherax boesemani often drags and stores food in their hiding spots for later consumption. Check them from time to time to prevent any bacterial contaminations.
- Crayfish need diversity in food. Do not give them the same food all the time. Change their diet periodically.
You can read more about it in my articles:
- Indian Almond Leaves and Alder Cones in a Shrimp Tank.
- How to Blanch Сucumbers and Zucchini for Shrimp, Snails and Fish the Right Way.
Is Cherax Boesemani Plant Safe?
No, Cherax boesemani is not plant safe. Like most crayfish species, they will try to eat, cut, shred, and uproot everything in the tank.
Therefore, it is not recommended to keep them in planted tanks. The only viable options for this species are:
- Plastic plants,
- floating plants,
- some cheap plants that you are ready to lose.
You can also read my articles:
Cherax Boesemani: Calcium and Molting Cycle
In order to grow and/or restore lost limbs, Cherax boesemani must regularly molt (shed the old exoskeleton). Growing a new exoskeleton requires a high amount of Ca to facilitate calcification.
The process of molting puts crayfish in a vulnerable state. That is why it is crucial to have many hiding places in the tank. In some cases, we can even use a divider in the middle to protect them from other tank mates.
Keeping and Housing Cherax Boesemani
Keeping Cherax boesemani is not complicated because these crayfish do not have special requirements. In addition, this species is pretty hardy and can withstand varied ranges of water parameters.
Nonetheless, before you start, make sure that the tank is properly cycled. Don’t forget to do a 15-20% water change a week.
Cherax boesemani requires a large space to survive because of their growth potential. Hence, a 20 gallon (long) tank (~80 liters) is a recommended tank size per one adult crayfish.
Important: All crayfish species are very good escape artists. They are known to be able to climb vertical surfaces, and often they use this ability to escape from any tank. These crustaceans are also pretty strong and can move light lids. So, a tight-fitting lid is essential.
Temperature: Based on their tropical native range, Cherax boesemani prefers water
temperature was between 75 – 88 °F (24 – 31°C), with an average of 79 °F (26°C). Under lower temperatures, their metabolism slows down and they become even less active than usual.
pH: In home aquarium, pH should be provided for this species in the range of 7.0 – 8.0. However, in their natural habitat, because of seasonal fluctuations, they were also found in water with a pH of approximately 6.4.
Hardness: They will appreciate optimal KH 3 – 20 and GH between 3 – 25 GH.
No special requirements.
Cherax boesemani can be kept in any tank with any substrate.
No special requirements.
Cherax boesemani is a nocturnal species. Basically, you can choose whatever you like.
There are only two options here – Hang on the back and Canister filters.
Having sponge filters in the aquarium with Cherax boesemani is just a very bad idea. Eventually, these crayfish will definitely chip, chew and break apart the sponge.
Decorations and Hiding Spots:
The aim of incorporating decors in an aquarium is to replicate its natural habitat and provide the best environment for the crayfish. Artificial shelters are essential and they should be abundant in Cherax boesemani tank set up.
I repeat they need hiding places to thrive and survive. Providing shelter during the mating season is also important as it offers protection during periods of vulnerability such as molting, protects the broodstock against predation, and minimizes aggressive interactions.
Some examples include stacks of PVC pipes, coconut huts, mesh bundles, driftwood, stones, etc.
Important: Crayfish do not like hiding spots with only one way out. They also prefer tight-fitting places.
Sexing Cherax Boesemani
This species is sexually dimorphic. There are several indicators that give away the gender of Cherax boesemani.
- Claws. Males have much larger and longer claws than females. In addition, only the males have a white patch on the yellow parts of their claws.
- Shape. Females have a wide tail; their carapace is also slightly bigger.
- Abdomen. Males crayfish have two L-shaped appendages (semen transfer organs) behind their 5th (last) pair of walking legs called claspers. The females have a circular semen receptacle between the bases of the last two pairs of walking legs.
Breeding Cherax Boesemani
Maturity and Mating:
- Depending on the temperature, Cherax boesemani becomes mature when they are about 8 – 10 months old.
- The males do initiate the process and use the claws to grasp and hold the female during mating.
- After fertilization, eggs develop inside the mother’s body for 4 to 6 weeks.
- After that period, the eggs transition to the outside of the mother’s body and rest on the female’s tail.
- Their eggs are pretty large: 3 mm long, 2 mm wide. Females use their appendages to keep the eggs clean from dirt and well oxygenated.
- Females can carry up a little bit over 100 eggs on average. The size of the female positively correlates to the number of eggs she can carry.
- Depending on the temperature, the eggs will hatch in 40 – 50
- Even though they don’t seem to be particularly aggressive towards the young crayfish, it is still recommended to keep juveniles in a separate tank with the same water parameters.
- Compared to adults, tiny Cherax boesemani will need more protein to grow and in the absence of food can start cannibalizing fast.
- Babies are very secretive and hide most of the time.
- Juveniles start getting colored when they are around 2 months old.
Cherax Boesemani and Suitable Tankmates
Even though these large crayfish are not extremely aggressive, they are still not completely peaceful and inoffensive.
Cherax boesemani can also be antagonistic and territorial (especially males). Therefore, it can be risky to house multiple crayfish in the same tank.
Ideally, Cherax boesemani are usually better in solitary confinement. Multiple Cherax boesemani should be kept in groups of one male with 1 – 2 females. In this case, crayfish should be well-fed at all times and there must be a lot of hiding places. Nonetheless, even this way it is not possible to completely avoid aggression.
No aggressive fish should be kept in the same tank with them.
At the same time, any fish that swim near the bottom of the tank is not a good option. The same is true of slow swimming fish. Cherax boesemani may behave aggressively towards a fish if they feel threatened.
Note: Even though it is possible for crayfish to coexist with fast top-dweller fish I would still not recommend it.
Snails and Shrimp:
Snails will definetely become crayfish food. They may grab anything passing, swimming, or crawling by.
As for the dwarf shrimp, adult Cherax boesemani usually do not pay any attention to them. In addition, shrimp are too fast for these crayfish.
Nonetheless, any molting shrimp is an easy meal for a crayfish. If crayfish gets hold of a shrimp, the shrimp usually does not have any chances.
Personally, I never recommend keeping even dwarf crayfish species with shrimp.
Bad Tank Mates:
- Any other crayfish species.
- Other freshwater crab species.
Although this species is not traded as ornamental very often, its popularity seems to be rising.
With their striking coloration and hardy nature, Cherax boesemani can make great aquarium pets if you understand their diet preferences, behaviors and care for them accordingly.
However, be careful and check your state laws – this species can be banned in some states.
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- Lukhaup, Christian. “Cherax (Astaconephrops) pulcher, a new species of freshwater crayfish (Crustacea, Decapoda, Parastacidae) from the Kepala Burung (Vogelkop) Peninsula, Irian Jaya (West Papua), Indonesia.” ZooKeys 502 (2015): 1.
- Patoka, Jiří. “Crayfish of New Guinea: Current status, exploitation and threats.” Evolution, Habitat and Conservation Strategies. Nova (2020): 43-70.
- Hidayah, Taufiq, MarsonMarson, Muhammad Ali, Ni Komang Suryati, and Dina Muthmainnah. “Fish Diversity and Water Quality of Ayamaru Lake, West Papua.” Sriwijaya Journal of Environment 6, no. 1 (2021): 1-7.
- vanKuijk, Tiedo, Jacobus C. Biesmeijer, Berry B. van der Hoorn, and Piet FM Verdonschot. “Functional traits explain crayfish invasive success in the Netherlands.” Scientific reports 11, no. 1 (2021): 1-12.
- Faulkes Z. 2015. The global trade in crayfish as pets. Crustacean Res 44: 75–92.
- S. Fish and Wildlife Service. 2017. Cherax boesemani (a crayfish, no common name). Ecological Risk Screening Summary. Revised Edition.