Breed: Yabby and Marron
Cost: $9.95 – $21.95
Lifespan: up to 3 years
Recommended for: aquatic critter fanciers
Australia has over 100 species of crayfish. Crayfish are lobster-like freshwater crustaceans found in a variety of habitats such as rivers, streams, dams, lakes and swamps and include smooth-bodied species such as the Yabbie, Marron and Redclaw.
Each of these have an enlarged pincer-like first pair of legs and their common name depends on the geographic area they inhabit. In New South Wales and Victoria they are called Yabbies (Cherax destructor); in Western Australia, the Marron (Cherax teniumanus) ; and in Queensland, the Redclaw (Cherax quadricarinatus).
These Cherax species are the best known of the Australian species of crayfish and are the only species sold as pets in Australia. Pet crayfish are a relatively new phenomenon and they have actually been a native food for many thousands of years. Yabby and marron catching is still popular in country dams and they have become increasingly popular in the gourmet dining scene.
The yabby is the most hardy of crayfish. In its native habitat, it can tolerate poor water conditions and long periods of drought by burrowing deep into river beds or dam walls to stay moist. This is how it actually earned the name ‘destructor’ – because of the damage it can cause dam walls and levee banks after burrowing.
Crustaceans are invertebrates, they are without a spine or bones and are protected by a hard outer casing, forming plates of calcified material which interlock to provide a shield-like structure around the animal’s body.
Yabbies vary widely in colour from dark greens, brilliant blues and near- white. Adults can grow to be over 25 cm (9.8 inches) and 300g but most commonly are 13cm (5 inches).
Red Claw varies in body colour from bluish-green to brown whilst the claws have obvious red patches. Adults are the same size as the yabby.
Marron usually vary in colour from brown to black but a striking blue form is now selectively bred and has become increasingly popular as a pet. This is the largest species of Cherax and has been recorded at up to 38 cm (15 inches) with weights of 2.5-2.7 kg. Pet adults are most frequently around 20 cm (7.8 inches).
A crayfish’s colour is in part influenced by the colour of the water. As the animal grows, it sheds its hard exoskeleton and produces a larger one. At each moult, the colour of the new exoskeleton will be influenced by the water colour. Muddied waters can produce darker crayfish, whilst blue and clear water can help produce the popular brilliant and iridescent blues and whites.
Crustaceans also have the ability to regenerate lost limbs, a handy trick considering limbs and claws are often lost during fights with other crustaceans. The limb will start to grow back at the next moult, however total regeneration is not immediate and may take several moults to complete.
Crayfish are very territorial and don’t have those big claws just for looks. Overcrowding will cause continuous fighting, and any unsuspecting fish which also happen to get too close may end up between the large claws. Crayfish are opportunistic feeders and will sample anything within their reach.
Crayfish are principally vegetarian and feed most actively at night. It is best to feed them water weed and thinly cut vegetable such as celery, potato, pumpkin, apples and other fruits. Your pet will also appreciate a regular supplementation of chicken pellets or a little lean meat.
Crayfish can live for months without eating (though growth and overall health will be diminished) and it is better to feed small quantities at a time. One-to-two small pieces of feed every two to three days is sufficient, removing left-over food after two hours to avoid polluting the water.
As long as water quality and feeding is maintained, these crustaceans will remain free of any significant diseases or health issues. Porcelain disease (or ‘white tail’ / ‘white muscle’ disease) may occur if cannibalism of dead or dying crayfish is allowed. It is invariably fatal and is evident by a conspicuous whitening of the exoskeleton under the tail. Deaths from fighting rarely occur, however a crustacean which has recently moulted will have a very soft exoskeleton and is vulnerable to severe injury or death from other crustaceans. Promptly remove any dead crustaceans from the tank.
Each crayfish requires no less than a 40cm area and structures to hide in.
Crayfish, especially the yabby, require very little maintenance and will live from 2-5 years. Although not absolutely necessary, a good aeration system is advised however under-gravel filters are not recommended as the burrowing crayfish will uncover the filter – reducing its efficiency.
Provide up to 5cm of sand under a layer of pebbles to allow burrowing, plus hollow structures, rocks and plastic waterweed. Natural weed may be used, but will be quickly shredded by inquisitive nippers.
Crayfish can be great escape artists and will climb air hoses and silicon sealant. Provide a suitably fitted lid for the tank.
Ideal water temperature for these three crayfish is 23°C – 28°C. Change the water regularly in small quantities (equal to a total water change every two to three months). Marron are less tolerant of poor water quality than yabbies.
The water should be alkaline (pH7.5 – 10.5) and should be ‘aged’ with chlorine removed before introducing crayfish. They are particulary susceptible to chlorinated water.
Breeding and cost
Sex can be fairly easily determined. Males have reproductive papillae at the bases of the last pair of walking legs and females have oval openings on the bases of the third last pair of legs.
Breeding marrons and yabbies is fairly easy and is usually achieved through simple co-habitation of the tank. The male will deposit a sperm packet near the female’s reproductive organs. She will then pass out eggs which will cross through the sperm packet, fertilising them. The eggs are then stored at the underside of the tail and carried until they hatch 8-10 weeks later.
Small, growing crayfish will moult every three to four weeks and the length of time between moults will increase as the crayfish gets older. Full grown animals moult once a year. Eating and activity is reduced during moulting. Once the shell is removed the animal will hide until the shell has hardened. Leave the old shell in the tank as the crayfish will often eat it (it’s a good source of calcium).
Crayfish prices ranges in cost from $9.95 to $21.95, depending on size and type. A start-up tank, suitable for two yabbies, will cost around $100 and includes a 12 litre tank, gravel, food, plastic weed and a filtration pump.
Anyone who likes a slightly different aquatic critter. Yabbies are very popular with children, are low maintenance and will grow to significant sizes if maintained properly. Of the three Cherax species, the yabby is the most hardy and easiest to maintain. It is more forgiving of varying water quality and come in a wide range of colours.
We filmed this segment at Kellyville Pets, Kellyville NSW. Phone (02) 9629 3282. Yabbies and other crayfish are available from many pet stores. For the nearest pet store near you, look under ‘Pet Shops’ in the Yellow Pages®.