Phylum — Arthropoda.
Subphylum — Crustacea.
Class — Malacostraca.
Order — Decapoda.
Family — Parastacidae.
Genus — Cherax.
Cherax crayfish from Australia and New Guinea.
All currently common southern Cherax crayfish (Parastacidae) belong to the group of medium and large-sized freshwater crayfish. This does not always mean that huge aquariums are necessary for them. However, they gladly inhabit large spaces with numerous hiding places. Cherax crayfish species can be very interesting aquarium inhabitants.
While crayfish such as Cherax destructor, Cherax quadricarinatus (Redclaw crayfish, Australian blue crayfish), or Cherax lorentzi roam the aquarium during the day and are easy to observe, their colorful relatives from New Guinea spend the days in caves or crevices, becoming active only after the aquarium lights are turned off. Maximum activity and feeding occur at night or under low light conditions.
Cherax can be quite aggressive towards each other. As a rule, they are very peaceful and with their large claws so helpless that they can coexist with any fish that, for their part, will not act aggressively toward them. Since Cherax crayfish spend most of their lives in hiding, aquariums must be well structured. Ceramic tubes, coconut shells, stone slabs, and driftwood can be chosen as decorative items.
When interacting with each other, Cherax crayfish are much more restrained than their American relatives. In contrast to northern hemisphere relatives, male Parastacidae possess gonopores rather than gonopods (copulatory legs). Unfortunately, this is not always a hundred percent male indicator. In some animals, gonopores are reduced, and some individuals are even hermaphrodites or capable of changing sex multiple times throughout their life cycle. Therefore, crayfish of the genus Cherax are very demanding when choosing a partner. Pairing them in captivity is difficult because the female may reject the male living in the aquarium, despite both specimens being ready for reproduction.
If you select a pair of animals, they will not start mating immediately. Actual mating always takes place in the dark and inside a protected shelter. After a prolonged courtship ritual, the transfer of spermatophores (sperm packets) begins, for which the partners must press their abdomens closely together. Spermatophores are glued near the female’s genital opening. After some time (which can take minutes, days, or even months), the female squeezes eggs from the oviduct. Enveloped in mucus, they dissolve the tough shell of the spermatophore and are fertilized in the process. During this period, the female leads a particularly solitary lifestyle. Young Cherax crayfish grow much slower than Procambarus crayfish, but the lifespan of this group of crayfish is significantly longer. While Procambarus clarkii rarely live more than 3 years, many Cherax crayfish live up to four or even 8 years.
Genus Cherax.
— Cherax (Astaconephrops) boesemani [Lukhaup & Peckny, 2008] — Brick Red, Purple Crayfish, Blue Moon. “Hoa Creek”, “Blue Moon”, “Red Brick”. New Guinea. Rightfully occupies a leading position in variety and extravagant coloration. Males are brighter in color and look more massive, the abdomen of males is somewhat thicker than that of females, the sex organs of males are located in the region of the third pair of legs, and in females — the first pair. Males are distinguished from females by the presence of a white blister-like spot on the back of the claws.
Subspecies “Blue Moon” — Blue Moon. The Blue Moon crayfish owes its name to the special shape of its spread claws, resembling two half-moons that form a full moon together. The outer lateral surface of the claws is colored in a bright orange color, as is the upper part of the tail lobes. The main body color of the crayfish is blue with a steel sheen. Smooth transitions of the two colors seem to form mysterious moonlines, and the entire body of the crayfish is covered with fine, barely noticeable speckles. In males, the lower surface of their claws has a white blister-like spot that appears only in sexually mature individuals; females, even in adulthood, lack this decoration;
Subspecies “Hoa Creek” — Magnificent purple crayfish. A dark purple back gradually gives way closer to the head and tail to dark pink shades, passing through the entire color palette from bright purple to delicate pink. The abdomen is dark purple as the dominant tone, turning black in places; interestingly, the purple color on the sides of the crayfish smoothly transitions into pink and purple shades of the back;
Subspecies “Red Brick” — Brick red crayfish. A saturated red or even scarlet main tone of the entire body of the crayfish could be called the strictest and simplest coloration among the three color variations, were it not for a light, almost imperceptible blue or light-blue tint along the entire back of the animal, smoothly transitioning into a more saturated blue color on the lobes and head. The claws of adult specimens acquire a bright blue-red color upon reaching sexual maturity, becoming black at the tips. The legs are also dark blue or blue near the base, smoothly transitioning to black at the ends;
For keeping at home, an aquarium of at least 70 liters in volume for one pair is suitable. Ideally, these crayfish should be kept in a group — several males and females together. To avoid settling scores and fights for free territory, the aquarium should be equipped with a large number of hiding places, for which ceramic grottoes, piled boulders, and driftwood forming burrows are best used.
Aquarium substrate is best used as a medium-fraction sand-gravel mix, carpeting the bottom with a layer of sea almond, beech, oak, or hazel leaves. They eagerly eat scalded spinach, carrots, and green peas, as well as crustacean foods in both flakes and pellets. Cherax boesemani crayfish are not as easy to breed as some other members of the genus. Temperature 23–27 °C.
— Cherax cainii [Austin, 2002] — Papuan Freshwater Crayfish, Australian Cobalt Blue Giant Crayfish, Marron. “Marron crayfish”, “Australian Cobalt Blue Giant crayfish”. Until recently, this crayfish was named Cherax tenuimanus. Western Australia and New Guinea. A successful object of commercial aquaculture. Crayfish grow to truly gigantic sizes, about 40 centimeters long and up to 3 kg in weight, females are much smaller and more graceful.
The coloration of these crayfish is usually brown, but brightly blue specimens are also found, which are specially selected for aquaria and sold separately. The peerless sky-blue coloration of the crayfish will more than make up for all the “inconveniences” possible during its maintenance. Like other crayfish of the genus Cherax, males have more massive claws and a sleeker, thinner abdomen. It is characterized by slow growth in the first year of life. Similar to Cherax tenuimanus, but the main difference is that it has a shaggy carapace, whereas Cherax cainii is glossy and smooth.
Crayfish are quite aggressive towards their own kind, and this must be taken into account when keeping them in an aquarium, since the minimum bottom area should be 150 x 50 cm for each adult specimen. Aquarium size — at least 300–400 liters, length from 150 cm, and preferably even more. High aggressiveness towards conspecifics under high stocking density. Unlike most other crayfish, they do not build burrows. Sand and stones are used as substrate, and the presence of grottoes and ceramic shelters in the aquarium is mandatory, where crayfish often like to spend time. They look especially spectacular on fine light sand.
Feeding in aquariums should be varied and brought as close to natural as possible: young tree shoots, vegetables, fish, and insect larvae are the favorite diet of Cherax cainii. You can also supplement the crayfish with dry food for aquarium fish. Water temperature should not exceed 24 °C, but the optimum range is 15 to 20 °C. They live 10–15 years. dH 3–18°; pH 7.0–8.5.
Cherax cuspidatus, destructor, quadricarinatus.
Cambarellus patzcuarensis, puer, shufeldtii. 
