Cherax quadricarinatus (Redclaw Grayfish) Back in 1985, I started a semi commercial venture breeding Redclaw Crayfish for the commercial market. My set up consisted of four 5,000 litre above ground swimming pools, set side by side with an overflow water exchange feature, a swimming pool pump and a pool sand filter. Water pick up for filtering was regulated from each pool passed down a common pipe to the filter, and from there the water was returned to the ponds via a spray system from above. This ensured that the returning filtered water was well airated for the redclaws. My initial stock consisted of about 400 wild caught Redclaws from Northern Queensland split roughly between the four pools. About three weeks before stocking I seeded each pool with about 10 kilos each of mud from a local dam and cow manure from a dairy farm,to set up the bio eco system that the cray's would need This venture ran well for about three years, I was supplying my restaurant and others with live crayfish an a weekly basis. AND THEN!!! the government started to interfere by imposing strict live fish trading rules and introducing very expensive licensing fees. Unfortunately, The combination of both were enough to force me to close down my enterprise.
(Cherax Quadricarinatus)! Redclaw Crayfish also known as the Tropical Blue crayfish,and Australian Freshwater Crayfish. Redclaw crayfish are a moderately large crayfish, and can reach lengths of over 90 mm and weigh in anywhere between 300 and 600 grams. They have a smooth body which is greenish/blueish in colour, the male of the species is distinguished by a bright red colouring on the margins of their large claws. The Redclaw is native to the upper reaches of the rivers in north eastern Australia and Papua New Guinea. It's preferred habitat is in high turbidity,slow moving streams or static waterholes. Redclaw prefer sites with abundant aquatic vegetation that provides cover. Redclaw do not burrow into the riverbanks like other Cherax species but prefer to hide in natural depressions,under rocks or amongst vegetation. Female Redclaw brood their eggs for six to ten weeks, depending on temperature. Most produce between 300 to 800 eggs per brood and they sometime breed five to six times per season. Water temperature is important for breeding with the preferred range being 23 C to 31 C. Hatchling's resemble the adults and remain attached to the undersides of the female for several weeks before becoming independent male Redclaw
Redclaw are NOT good aquarium tank mates, DO NOT KEEP THEM IN WITH OTHER FISH OR PLANTED TANKS. Although more placid than their other Charex cousins, they can get very agro when they have a mind to. My tip is to house them in a large aquarium 60 cm or larger with plenty of structure for hiding places so as they can get away from each other especially during times when they are moulting. The female also becomes very territorial when berried. FEEDING: They are omnivores but tend to eat more vegetable material, I have known them to munch into driftwood in their tank, they are not good fisherman being slower than other Cherax species, but that does not exclude fresh fish from their diet. They do like chicken pellets, a very small piece of red meat , worms, and fish.
I found that water temperature at around 25C to be good ( don't go up to 31C) good filtration with plenty of surface movement. PH between 6 and 7.5 although they can stand higher. Selective Breeding : I found the Redclaw to be relative easy contender for selective breeding ,having success in breeding a beautiful deep blue, pale blue, a deep green and an almost albino over successive generations. I also found that sometimes they will revert back to their original colours when severely stressed. I hope that this article will help some of you who are contemplating keeping Redcaw Crayfish.
Male Blue Female White
Disclaimer : The information contained in this article is purely from my own experiences and is by no means intended to be completely right in my findings Wayne Summerhayes
Australian Freshwater Crab
Freshwater crabs can be found in the tropics and subtropics in most parts of the world. Out of a total of 6,700 species , there are more than 1,300 described species of freshwater crabs,and many more currently unknown to science.
The IUCN (International Union for Conservation of Nature ) Red List has assessed all described species as “ data deficient”, as data on their ecology, reproductive biology and habitat requirements is lacking.
The majority of species studied to date tend to occur in small geographic areas, have poor dispersal abilities and low fecundity (the ability to produce an abundance of offspring) thus making them highly susceptible to land use alterations, river regulation changes and climate change.
Scientists in Australia are investigating the biology and ecology of our remarkable freshwater species in the tropical regions of northern Australia and the Torres Straits. Very little is known about many of the far northern species, however science has discovered that they have an amazing lifecycle, these crabs will dig tunnels in the creek banks at the end of the wet season and spend the hot and dry times in a prolonged state of torpor/dormancy, emerging again at the onset of the next seasons rains presumably to feed and reproduce. Females of the species A. Transversa have been documented carrying their young
under their abdomen underground during the dry season and when the wet season arrives they will leave their mother growing up quickly before the next dry season.
The most common species of freshwater crab found in the aquarium market in Australia are the Holthuisana sp. (Austrothelphusa) There are several sub species in this order:
With the most common on the market being A. Transversa and A. Agassizi :
A. Agassizi (Freshwater Brown Back Crab)
The two species A.Agassizi and A.Transversa are by nature amphibious and should be provided with an “Island” where they can leave the water at will . It seems they require atmospheric air for their gills to operate properly.
In nature these crabs frequent inland rivers and billabongs in northern Australia that dry up in the winter.
Temperature: 18 deg C. to 25 deg C.
pH: 6.5 ------7.5
General Hardness Soft /Moderate
The freshwater crab can not survive for long in very acid water. Make sure their wateris free from ammonia,nitrate and copper.
A true scavenger, they will eat most types of sinking fish food, blood worms, fresh vegetables
and sometimes aquarium plants.
Colour and Varieties:
The A. Agassizi ( Brown Back Crab) can come in a variety of colour patterns e.g with an attractive pale fawn colour, with a chocolate brown irregular band crossing from front to back of the carpace or even a tiger stripe pattern. While the Colours of A. Transversa is mainly a shade of brown from yellowish to deep redish.
Both species are great escape artists and can easily climb the silicone in the corners of most tanks. I have had them climb up air hoses and the water pick ups for the filters.
They are fairly peaceful and can be trained to come to your fingers for food. If kept in a community tank ensure that there are no slow fish as the crabs are not adversed to a little fresh fish in the m
Disclaimer: A. Transversa
The information provided here is of a general nature only.
Citation: The IUCN red list
Dr Nathan Waltham: Ecology of Freshwater Crabs in Tropical northern Australia