Cherax quadricarinatus

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Cherax quadricarinatus, also called Redclaw Crayfish or Red Scissor Crayfish, is a large freshwater crustacean native to northern Australia and New Guinea. Its bluish to brownish-green body, strong claws, and the red markings found on adult males make it a striking aquarium animal. This wild-collected species is offered with intermediate availability, so careful selection is worthwhile. It is nevertheless a territorial, powerful, and opportunistic crayfish that requires a suitable layout, warm water, and carefully planned tank mates. With enough space, stable water quality, and secure shelters, it can become a fascinating long-term aquarium inhabitant.

General species description

Cherax quadricarinatus is a large freshwater crayfish belonging to the Parastacidae family. It mainly inhabits tropical streams, billabongs, and quieter areas connected to rivers. In aquariums, it is most active at dusk and during the night. Despite its impressive appearance, it can be kept successfully when provided with adequate floor space, numerous hiding places, and well-filtered water. Its behavior remains territorial, especially around shelters and during moulting. Recently moulted individuals are vulnerable and must be able to hide undisturbed. This crayfish may collect and move gravel, uproot plants, and capture slow or weakened animals. It is therefore better suited to a species aquarium or a very carefully planned setup than to a standard community tank.

Geographical origin and biotope

Countries of reference: Australia and Papua New Guinea. Cherax quadricarinatus is associated with tropical regions of northern Australia, especially Queensland and the Northern Territory, as well as southern New Guinea. Its habitat includes rivers, streams, waterholes connected to waterways, and areas affected by seasonal changes in water level. Water is generally warm and neutral to alkaline, and may be clear or slightly loaded with organic matter. The bottom alternates between sand, gravel, mud, and plant debris, with roots, branches, and banks providing shelter. Flow ranges from slow to moderate depending on the location. In an aquarium, this diversity can be reproduced with tubes, stable rocks, roots, and shaded areas. Tropical temperatures and good oxygenation are important for growth and successful moulting.

Precise locality and local name

Within its natural range, Cherax quadricarinatus occurs in northeastern Australia, particularly tropical Queensland, and in the northern part of the Northern Territory. It is also native to southern New Guinea. The most common local English name is redclaw crayfish, a name also widely used in Australian aquaculture. The commercial name Red Scissor Crayfish refers to the red coloration of the claws in adult males. Depending on the population and age, the general body color can range from blue-grey to olive brown. This crayfish has also been introduced to several tropical regions for aquaculture or the aquarium trade. Local regulations concerning possession and transport should therefore be respected, since crayfish can become invasive when released into natural waterways.

Appearance and physical characteristics

Cherax quadricarinatus has a robust body, a thick carapace, and large claws. The base color ranges from dark blue to greenish brown, sometimes with paler tones along the sides. Mature males usually have bright red to reddish-orange claws, a distinctive feature behind its common names. Females may show less pronounced markings. The antennae are long, and the walking legs are well developed for moving across the bottom. Adult specimens may become substantial, reaching about 25 cm in total length under favorable conditions. Like other crayfish, growth occurs through successive moults. An empty shell left after moulting should not be removed immediately, since it may be eaten and help recycle minerals. Hiding places are essential throughout this cycle, particularly during the vulnerable period following a moult.

General diet

Cherax quadricarinatus is an omnivorous and opportunistic feeder. It consumes plant debris, softened leaves, algae, vegetables, sinking foods, and various small prey items. In an aquarium, a staple diet of complete crayfish pellets can be supplemented with zucchini, spinach, peas, or properly prepared catappa leaves. A regular source of calcium supports shell development, especially after moulting. Animal foods such as worms or small pieces of mussel may be offered occasionally, but excess protein can contribute to poor water quality. Uneaten food should be removed promptly. The diet should remain varied while being based mainly on plant matter and complete foods. Cherax quadricarinatus may also catch slow fish, shrimp, and snails, so it should not be considered completely peaceful. Sinking food should reach the bottom before the aquarium lights are turned off.

Essential data

• River of origin: Fitzroy River, among the drainage basins associated with its Australian range
• Local name used: Redclaw crayfish
• Origin of the scientific name: Cherax is a Latinized zoological genus name; quadricarinatus describes four keels or ridges on the carapace
• Full-name etymology: quadri means four and carinatus means keeled or bearing keels
• Common or vernacular names: Redclaw crayfish, Red Scissor Crayfish
• Family: Parastacidae
• Subfamily: Parastacinae
• Name pronunciation: KER-aks kwad-ri-ka-ri-NA-tus
• Discovery: Eduard Carl von Martens, 1868
• Maximum adult size: About 25 cm
• Water temperature and pH: 24 to 30 °C; pH 6.5 to 8.5
• Stream appearance and surrounding vegetation: Slow to moderately flowing tropical waters bordered by riparian vegetation, roots, and plant debris
• Typical tank mates: Glossamia aprion, Oxyeleotris lineolata, Melanotaenia splendida, Leiopotherapon unicolor, Tandanus tandanus, Amniataba percoides
• Temperament and behavior: Territorial and opportunistic; mainly active in the evening and at night; may catch slow animals
• Water depth: Shallow to intermediate sections of waterways and billabongs
• Sexual dimorphism: Adult males generally have larger, more noticeably red claws; females have a broader abdomen for carrying eggs
• Bottom structure and flow: Sand, gravel, mud, roots, and debris; slow to moderate flow depending on the area

In your aquarium

Cherax quadricarinatus can be a spectacular and interesting animal to observe, but it requires a secure setup. Provide a spacious aquarium, a tightly fitting lid, efficient filtration, and several sturdy shelters. Keep the water warm, stable, and well oxygenated, paying particular attention to nitrate levels and moulting periods. Fish compatibility remains risky because slow tank mates may be injured or eaten. A varied diet rich in plant matter and supported by a calcium source promotes steady growth. Finally, never release this species into a natural waterway; its potential to establish populations makes responsible aquarium keeping essential.