Blue Moon Crayfish (Cherax gherardii)

Blue Moon Crayfish Cherax gherardii
Name	Blue Moon Crayfish
Name Lat.	Cherax gherardii
Synonym	Cherax sp. 'Blue Moon'
Family	Southern Hemisphere Crayfishes
Family lat.	Parastacidae
Order	Decapods
Order lat.	Decapoda
Origin	New Guinea
Habitat	Streams
Diet	Crayfish food, leaves, carrion
pH	6.5-7.5
Behavior	Peaceful
Keeping	Individual, pair, group
Care Level	Moderate
Reproduction	Oviparous
Breeding	Moderately difficult
Life Span	4-6 years
Protection	No
Metric Units
Size	10-15 cm
Temperature	20-27 °C
Hardness	5-15 °dH
Aquarium	~ 150 l
US Units
Size	4"-6"
Temperature	68-81 °F
Hardness	89-267 ppm
Aquarium	~ 40 gal

Distribution and habitat

The distribution area of the dark blue crayfish is West New Guinea (Indonesia), where they occur in the clear, clean water of rivers, streams and lakes. There they prefer to live in the dense riparian vegetation.

Maintenance

They require a well-structured aquarium with roots, stones and robust plants, with hiding places (caves, crab tubes) and a moderate current. The burrowable substrate of sand or fine gravel should be partially covered with foliage (e.g. sea almond leaves, oak leaves), which also serves as food.

No ammonia, ammonium and nitrite should be detectable in the aquarium water, the nitrate value should not exceed 100 mg/l. To ensure water quality and oxygen content, a filter and heater adapted to the size of the aquarium is required, as well as lighting for the proper day-night rhythm of the animals.

Diet

They are omnivores that feed on animal organisms, carrion and dead plant material. For a balanced diet, feed once daily with a high-quality crayfish food (pellets, sticks) supplemented with insect larvae (live or frozen), fish, crayfish or shrimp meat, and foliage (e.g., sea almond, oak, beech). Occasionally, plant food in the form of spirulina, kelp or scalded leafy vegetables should be offered.

Unaccepted food must be removed after 2-3 hours. Regular and varied feeding promotes health and prevents deficiency symptoms.

Behaviour and compatibility

They behave peacefully within the species, but also towards other crayfish, therefore the keeping of several pairs or a group in a larger and richly structured tank is well possible. They can be socialized with not too small fish, such as rainbowfish or barbs. Also keeping them together with shrimps or snails is usually possible without any problems.

Basically, only compatible animals with similar demands on water quality and water temperature should be socialized.

Reproduction and breeding

Males can be identified by the gonopods (mating styli) on the posterior part of the underside of the body. During mating, the male turns the female onto her back shortly after her molt and transfers a sperm package with his gonopods. The female carries the eggs (50-100 of them) on her pleopods (webbed feet) and supplies them with oxygen by movement (fanning). Dead or non-developing eggs are eaten by the female. The young hatch after about 4 weeks.

Important

Each crab must have at least one cave (e.g. crab tube) of its own in which it can hide and also to be able to molt undisturbed

It can happen that a crayfish is missing a claw. Mostly these are females that have lost a claw during mating. The missing claw slowly grows back during the following molts. The strong claws are also used for digging.

The well-being of the animals should be checked regularly. Temperature should be checked daily, pH, hardness and nitrate levels at least every 14 days. Regular partial water changes are recommended, even if the contaminant level has not yet reached the upper limit. Sudden changes in water quality should be avoided. Newly introduced animals must be accustomed slowly to the water in the aquarium.

Further literature can be found in your pet store.

References

Text: Werner Winter; Image: Werner Winter

Source: LUKHAUP & PEKNY (2008): Süßwasserkrebse aus aller Welt, Dähne Verlag; ENGELMANN & LANGE (2011): Zootierhaltung - Tiere in menschlicher Obhut: Wirbellose, Verlag Harri Deutsch