Is my yabby a boy or a girl?

Most yabbies are either male or female, but some have characteristics of both, and are called ‘intersexes’.

A yabby, Cherax destructor
Photographer: Alan Henderson, Source: Museum Victoria

As in humans, the most reliable character to use to distinguish male and female yabbies is the position of the reproductive openings or gonopores. To see these openings you must turn the animal upside down and inspect the base of their walking legs. Live animals don’t like this much – watch the claws! There are five pairs of legs, called pereopods. The first pair are the chelae (also called claws or nippers) and the second to fifth pairs are the walking legs. The legs are attached to a narrow ridge called the sternum, the same name we give to our breastbone.

In males the gonopores are on the first hinging segment of the fifth pereopod or last pair of walking legs and are often seen as small bumps or ‘pimples’ (arrowed in left-hand diagram).

Look near the middle of the animal. In females the gonopores are on the bases of the third pair of pereopods, second walking legs (arrowed in right-hand diagram). It is a larger opening than in the male and looks transparent and oval-shaped. But make sure to look on the base of the legs, not on the sternum that runs down the middle of the animal’s belly, because in some species that ridge may have openings as well.

It is easy to pick the sexes when the animals are reproducing, or ‘in berry’. Only females carry the eggs. They carry their eggs on the appendages of the abdomen (the pleopods), and the eggs look like bunches of grapes. If you can find a female in berry, look for her genital openings on the second walking legs. Then you will know what the female genital openings look like and you can look for the same feature in non-reproductive animals.


                      Male                           Female
Illustration: Jo Taylor / Source Museum Victoria

Further Reading

Fallu, R., 1994. Yabbies for Fun, Fishing and Farming. Department of Food and Agriculture: Melbourne.

Kailola, P. J., Williams, M. J., Stewart, P. C., Reichelt, R. E., McNee, A. and Grieve, C., 1993. Australian fisheries resources. Bureau of Resource Sciences, Department of Primary Industries and Energy, and Fisheries Research and Development Corporation: Canberra.

Yearsley, G. K., Last, P. R. and Ward, R. D. 1999. Australian Seafood Handbook. An Identification Guide to Domestic Species. CSIRO Marine Research: Hobart.

Comments (133)

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archiearchiesmith 31 August, 2009 16:15
nice yabby
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Sally 20 December, 2009 14:41
I love yabbys as a mater of fact i have six and thanx to this website i now know which ones are female and male i have 2 female and 4 male
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Ben 17 April, 2014 21:19
Probably not a good thing. If you have a 2:1 ratio the males sometimes fight to the death over the females
Russel 13 January, 2010 17:50
can you send me a pic or tell me what do girl yabbys look like
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Discovery Centre 14 January, 2010 15:46

Hi there, Russel - please see above for a detailed description of how to differentiate male and female yabbies. The underside of the tail of a female is the one on the right-hand side of the illustration.

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Karen 6 February, 2010 06:44
We woke up this morning to find my sons pet crayfish "Robert", who has been acting weird with masses of creamy-yellow grapes under the tail area. I guessing that Robert is actual a female and she has eggs. She is our only yabby, what will happen to her eggs? Will they just fall off? And how will this affect her health? Do we need to do anything? Kind regards Karen
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Discovery Centre 9 February, 2010 15:10

Hi Karen - Yes Robert is certainly Roberta, and what you are looking at are in fact eggs. You don’t need to do anything special - just keep looking after her as per usual, but avoid any disturbances such as doing a major clean of the tank etc. If the eggs are infertile she will sort things out herself, and most probably eat them. If they are fertile you will ultimately see tiny babies clustered under her tail, which soon after will drop off and become independent.

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Keely 28 March, 2010 20:03
I just got Yabbies, 4, and the picture is confusing. I still can't tell if my yabbies are male or female!
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Discovery Centre 29 March, 2010 14:04

Hi Keely - Our Live Exhibits staff would be happy to help you discover the sex of your yabbies. Perhaps you could take some pictures of the yabbies you have just purchased as email them to us via our 'Ask the Experts' enquiry service. Please also read out 'Identifications' guidelines before you submit your enquiry.

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Keely 29 March, 2010 23:06
Hi, me again. Thanks for that. I just moved my yabbies from a small aquarium to a bigger one, at first it was like they were dead. some of them lay on their backs curled up in a ball, but when I reached in and touched them, they started moving again. after a while they stopped, but now the biggest one(Terien) is acting really weird, its acting like its drunk and sometimes it fights at nothing! please help, I don't want her/him to die.
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Keely 1 April, 2010 19:41
Its ok she stopped, but I would of liked it if you answered. HAPPY EASTER EVERYONE!
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Discovery Centre 3 April, 2010 11:55

Hi Keely! We're glad your yabby is ok, and Happy Easter to you too! For specific questions for which you need a timely answer, I'll direct you again to our 'Ask the Experts' service. Whilst we do check these comments threads for questions, they are more used for facilitating dialogue between visitors.

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Discovery Centre 6 April, 2010 10:27

Hi Keely, we have checked with our Live Exhibits team and they have suggested that perhaps your yabby was responding to a change in water temperature, or perhaps there were more additives in the water in the new tank, but it is great to hear that all is well with your yabby!

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megzy 10 April, 2010 20:38
down at our creek there are yabbies that have red eyes! why is that so?
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Keely 7 May, 2010 21:21
Oh please help me! The first time one of my yabbies moulted, the others attacked her! now she has no claws, three legs on one side and half a leg on the other! We moved her to a different tank, but she can't stand up. We don't know what to do with her and I love little Bubbles... can she still eat without her claws? is she alright lying on her backside (Yes, she is still alive) Do we have to kill her? :(
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Ben 17 April, 2014 21:25
Yeah that happened to ours the other day. It shed and got absolutely destroyed by the other yabbies. It has one leg and another yabby was eating it when I found it. When they shed it is wise to put them in a seperate tank. They are also extremely territorial animals so have plenty of hiding spots for them. And leave their shell with them when they shed. They will eat it and the nutrients will help their new shell harden faster
Keely 9 May, 2010 09:49
I'm sorry for the specific question, I was too worried to read it. Bubbles has died, But this morning Rocky moulted and she's fine! we are making sure the others don't fight her before she hardens. We want to do this right this time. I couldn't stand the flowing tears when Bubbles passed on. Thanks for everything!
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Discovery Centre 10 May, 2010 15:24
 

Hi Keely - It sounds like there is a fair bit of aggression and fighting going on with your yabbies. There can be a few reasons why they may be behaving that way:

*There may be too many yabbies for the space provided

*There may be too few hiding spots

*There may be not enough protein in the food, or food in general (ie attacking each other through desire to eat other yabbies)

 

It’s hard for us to say exactly which (if any) of these factors may be affecting your yabbies, as we do not know all of the circumstances.

 


 

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Andrew 5 June, 2010 22:19
Hello, after coming home to feed my yabby, i was astounded to see that both her claws have fallen off. Its almost like they've been disconnected. Both have just come off where they protrude from the body. She hasnt been eating a lot lately apart from that, i dont know. Any help would be appreciated.
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Libushe 27 June, 2010 16:24
My crayfish is picky eater. Does he need special menu to eat? (So far he eating frozen pees, dry shrimp and life worms.)I know the he need Calcium suplement in water, can I drop there "TUMS" tablet sometimes? Can I use also seltzer water to replace water in his tank? Thank you.Libushe
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Ryan 3 August, 2010 17:38
Hi, my pet blue claw yabby has tiny little bugs around it, mostly on the bottom of his body. Is this a disease or could it be babies? Thank you. Ryan
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Dibs Fitzgerald 17 August, 2010 15:10
Could you please tell me what a juvenile yabby is called?
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Discovery Centre 22 August, 2010 12:47

Hi Dibs, the term yabby is used for the large, native freshwater crayfish Cherax destructor. There is no special term for a juvenile yabby, they are just referred to as a juvenile yabby.

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claire 5 September, 2010 16:46
i have 62 yabbies in a 2cm tank
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Discovery Centre 7 September, 2010 12:48

62 yabbies in a 2 cm tank – that is a lot of mouths to feed in a very small space! At the museum we keep yabbies for display as well as breeding them to feed to other animals – including our Australian Lungfish in the 600 Million Years exhibition. We work out the minimum size / maximum number of individuals by watching the animals behaviour. If our yabbies do not have enough hiding spaces within the tank they will start fighting – leading to injuries and death. So as soon as we see this we separate our population and keep the numbers low.

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Aaron 21 September, 2010 16:09
I have a 80cm x 30cm tank. I have kept 1 lonely yabby for quiet a while now. I am looking at getting a few more. Are there any tips on how many would be too many? And if getting smaller ones and bigger ones will be a problem?
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Discovery Centre 24 September, 2010 11:10

Hi Aaron, it is always nice to have other animals in a tank – especially for one lone yabby. The only problem you may be faced with is that yabbies are quite territorial and you need to provide ‘hiding’ spots for all the yabbies. If you know if your yabby is a boy or girl, it might be nice to get him or her a boyfriend/girlfriend so you could see a whole life cycle. You should not keep more than 2 or 3 adult yabbies in a tank you described, but having babies in there would be great.

 

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Jenni 27 September, 2010 14:10
How long are yabbies pregnant for?
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Discovery Centre 29 September, 2010 16:52

Hi Jenni, eggs hatch after about 40 days of being stored under the female's tail, this amount of time can vary depending on the temperature of the water. Once hatched they spend the next couple of weeks continuing to be under her tail developing. So it can be a fair while before you have the tiny yabbies ‘free swimming’.

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Jen 5 October, 2010 00:05
Hi Discovery, I have a female Yabby with eggs, I don't know how long she's been carrying them for but I have noticed the eggs have started to change. I was wondering if you could provide me with further information. What to look out for in terms of the babies getting ready to leave? And what to do after they hatch and have left mums tail?
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Discovery Centre 7 October, 2010 11:59

Hi Jen, it sounds like your yabby eggs have hatched and the hatchling yabbies are currently in a stage that do not look like yabbies yet and are still attached to the females swimmerets under her tail. They will look like they have a domed shaped back for about three days and then moult again. At this point they look a bit more like a yabby but will still be attached to mum. They will remain this way for around 10 days until they moult again to look like a ‘yabby’. It is at this point that they will start to move away from mum’s tail and be a bit more active around the tank.

At this point when the young leave mum they will be looking for food to feed on. At the museum we try to provide small amounts of food at regular intervals. The young animals can’t fit much into their bellies and so need small meals daily. Apart from that they can be looked after the same way you look after your adults.

Best of luck from the Live Exhibits team

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Jen 7 October, 2010 19:39
Do I need to remove mum once the yabbies have hatched? Its not a large tank. Thanks a lot for your help :)
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Discovery Centre 11 October, 2010 11:07

Hi Jen, if you leave mum in the tank you will find she may nibble on some of the babies over the coming weeks. You will have a lot of young yabbies so losing a few here and there may not be too much of an issue for you. We have a tank here at the museum that is 4 foot and has held the mum and all her young successfully for the last couple of months. We provided lots of hiding spaces for the young to keep out of the clutches of their parent.

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Amanda 12 October, 2010 12:42
Hello my little yabby has the little whole thing u describe in the pictures above on the right hand side but on the second to last row of legs not the third row of legs would this still be a girl?
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Discovery Centre 27 October, 2010 10:06

Hi Amanda. It's hard to answer if your yabby is male or female as there could be a couple of things that may change what you are looking at. My first guess is to confirm your yabby has not lost any legs – if the last pair of legs have come off the yabby maybe this is what is causing the confusion.

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renee 1 November, 2010 20:04
my yabbie has eggs under it tail but the poor thing is on it side it looks like it is dying is this what they do or is she dying
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Discovery Centre 5 November, 2010 14:26
Hi Renee, it is hard to know what your yabby is up to. We generally have our females yabbies with eggs behaving just like normal – except they have their tail curled under to protect their eggs. Possibly the water conditions or her safe refuge in the tank has been disturbed and she is a little uncomfortable. Keep an eye on her and maybe do a partial water change to give her some fresh water.
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adam 8 November, 2010 23:02
one of my yabbys (i have two )has eggs should i take all my fish out and the other yabby so they don't eat the baby's and will snails kill the little baby's
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Discovery Centre 15 November, 2010 12:47

Hi Adam, once your yabbies leave their mothers tail refuge they can be potential prey for your fish. There are two main things you can do to help your young yabbies out. The best thing you can do is provide lots of hiding places for your young yabbies and this should help reduce the chances that fish will find them. You can also have a spare tank available and if you find your fish, and other yabbies eating your young ones when they emerge transfer them away. Otherwise, enjoy watching a food chain in progress. Once you fish have had their fill they should stop eating the young and it may be a great display tank.

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Kaiden 28 November, 2010 09:39
What is a baby yabbie called?
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Discovery Centre 29 November, 2010 12:28

Hi Kaiden, the term yabby is used for the large, native freshwater crayfish Cherax destructor. There is no special term for a juvenile yabby, they are just referred to as a juvenile yabby.

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Napooleon Poopins 4 December, 2010 15:42
my yabbie just had babies. is it safe to keep the young in the same tank as the mother. Will my yabbie eat her own young?
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Discovery Centre 6 December, 2010 14:10
Hi Napooleon, if you scroll back up this sheet to the 5th and 7th October and look at the questions and answers for Jen you should get the answers to your questions.
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Bj 8 December, 2010 10:47
Hi one of my older yabbies has become overtime completely white? is that just as they get older? and also i now have about a hundred living young in my tank (been alive for a round 9 months) they are progressively getting bigger, some are a pinkish colour while others are dark blueish. Is there anyway of distinguishing them via their colour? Thanks heaps :)
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Dana 8 December, 2010 19:33
Hi, one of my yabbies has these little things on the bottom of it's tail, i don't think there eggs but they sort of look like legs that are continuously running. What are they, and should i be worried? - thanks, Dana.
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Discovery Centre 9 December, 2010 12:24
Hi BJ - Our live exhibits staff say that yabbies generally lose their natural colour if kept out of sunlight for long periods, rather than becoming white through age alone. The loss of pigment exposes the underlying structure, which is naturally white. There may be some influence from the type of food they eat, but the main cause is generally lack of sunlight, and some colour may return if they once again experience natural light.
Young yabbies tend to be light pinkish or light blue and become darker as they get older, so the variation in colour in this case is due to age. Once again if they aren’t exposed to sunlight this dark colour will fade eventually to white as well.
Their colour doesn’t indicate anything other than the amount of pigment in their exoskeleton, and the sexes are distinguished by structures on the bases of the legs.
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Millie 14 December, 2010 14:57
Hello, I have three yabbies in my two foot tank and they all live really happily together, I was just wondering about this little thing they do. They will sit there and continually move one claw up and down. I have searched on the net but i still can not figure out what they are doing?
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Danna 16 December, 2010 00:12
i got a 10cm yabbie and it has lil black eggs i think under her tail can they pregnant that small?
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Discovery Centre 17 December, 2010 16:10

Hi Dana, the things you are looking at on the underside of your yabbies tail are most likely pleopods  which are also known as swimmerets. For female yabbies these are very important as the edge of each pleopod is lined with fine hairs, or setae, to which they attach their eggs. So you are looking in the right spot if you are looking for eggs.

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Discovery Centre 17 December, 2010 16:12

Hi Millie, we have checked with our Live Exhibits Team and unfortunately we do not have an answer for you.  It has been suggested that the yabbies here at the museum 'wave' a claw when they are reaching out for food, so perhaps that is what they are doing.

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danna 18 December, 2010 21:32
how come my yabbie standing on his claws like his stretchng
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david 7 January, 2011 12:46
i am getting a yabbie and i don't know if it is a boy or a girl can some one help me???
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Discovery Centre 8 January, 2011 10:35
Hi David, if you go back up to the information sheet before all the comments it explains how to tell if a yabby is a boy or a girl.
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Owen 9 January, 2011 17:02
Hi - we have two yabbies and we are sure they are both females and yet one has got eggs and is busy keeping them clean/protected etc. Is this possible??? Can a female yabbie have eggs without having a male? Will the eggs just remain under her tail until it's obvious that they aren't fertislised and then fall off?
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matt 16 January, 2011 12:26
I use yabbies as cod bait!
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YABBIE HUNTER 20 January, 2011 22:56
yeah david mate its the YABBIE HUNTER, on your female yabbie you have 2 holes on its third legs up, and the male has two little prongs on its bottom legs
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Charlie 27 January, 2011 02:08
One of the baby Yabbies I was just given has a leg missing an little wriggling suckers all around the place the leg is missing and on it's back, are these water lice? I know they aren't babies. Is there anything I can do to get rid of them without harming the yabby? It keeps trying to pick them off but they crawl back go back on.
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Discovery Centre 11 February, 2011 10:45

Hi Charlie, the "wriggling suckers" sound like a common parasite to yabbies called Temnocephids, which are relatively harmless in low numbers. Other than manually removing them I can't think of any other way to get rid of them without having an effect on the yabby.

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hoani 16 March, 2011 19:23
hi i have three yabbies and i cant tell if i have any boys and girls i read all the comments and i still cant find if there boy or girl and i had four i had a black one but im not sure why it died but i woke up two days ago and it was lying on its back can some one help me please?
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Discovery Centre 18 March, 2011 16:08
Hi Hoani - sorry to hear you're having trouble with your yabbies. If you find you have no luck with the diagrams and instructions given above, then I would suggest you try exploring some of the documents listed in the "Further Reading" section.
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subi 15 April, 2011 07:00
my yabbie puts its tail in the air, just out of the water and waves its little paddley bit around, why would it be doing this?
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Nicholas 17 April, 2011 10:24
I have to yabbies and they aren't eating could you tell me what I can do?
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TROY 18 April, 2011 13:56
what is the best thing to feed my yabbies so they stay healthy and will they eat my guppies
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chung 28 June, 2011 12:17
Hi fellow yabbie lovers. i was just wondering whats your best recipe for the fantsatic creatures. my life partner and i are starting a yabbie resturant
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raymond 24 August, 2011 14:29
hey i got about twenty yabies and i was wondering how big the tank had to be
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Michaela 14 October, 2011 18:30
Hi I have 3 baby yabbies in a very big tank with alot of hiding places I recently came home to find that one of my yabbies ate another yabbie why is this?
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Discovery Centre 15 October, 2011 12:52
Hi Michaela,

Yabbies can be territorial and can become aggressive and cannibalistic if they don’t have enough space. The Australian Museum will provide you with some information on what your yabbies will require. 

 

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Courtney 20 October, 2011 21:08
I have a pet yabbie which has been fighting with its "brother" and now has no legs or claws. I have separated it into a nursery tank - it is eating and is staying alive. I know that yabbie legs and claws will grow back with moults, however i am anxious that it will have trouble moulting without any legs. After advice from the pet shop I have already put some shell grit in the tank to provide extra minerals for its shell. Is there anything else we can do to help it? is it likely to survive the next moult?
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Discovery Centre 31 October, 2011 11:46

Courtney, thanks for your query. We have asked for some comments from our Live Exhibits team here at Melbourne Museum, and they have said the following:

Yabbies will readily fight in captivity and a dominant yabby, if given the opportunity, may slowly dismember another one over a short period of time. A female yabby will also consume her offspring if they don’t have enough places to hide . When keeping yabbies together, the key is to provide as many hiding places as possible, so vulnerable individuals will always have a handy bolthole in which to escape. Some yabby keepers use thin strips of corrugated plastic, laid on top of each other, which affords a large number of cavities in a small amount of space.

While it is true that the limbs will grow back after successive moults, this process is slow. Very young yabbies may moult every week, but older yabbies may moult only once a year, depending on the food supply. Limbs don’t grow back completely after a single moult, but take several moults to get to a usable size.  Depending on the age of your yabby, the limbs may take a very long time to return, if ever. In the meantime, your yabby will be unable to move around under its own power, other than the occasional tail-flick.

In addition to the yabby’s quality of life, there is also the question regarding pain and suffering. This subject has been widely debated for many years, and a 2005 report by Advocates for Animals, entitled ‘Cephalopods and Decapod Crustaceans – Their Capacity to Experience Pain and Suffering’, stated there was evidence that suggested “there is a potential to experience pain and suffering in these animals”. As the yabby’s carer, its fate is up to you. If you choose to euthanase, a report by the Australian and New Zealand Council for the Care of Animals in Research and Teaching, entitled ‘Euthanasia of Animals Used for Scientific Purposes’ recommended a number of euthanasia methods but the simplest method was to place in the fridge to cool the animal down, and then to freeze.

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Joanna 2 November, 2011 12:25
Hi, i have two yabby's the bigger of the two has egg's/larvae under her tail. i have read on here that its ok to leave both the mother and the male yabby in the tank once the babies rome free. i was concerned about this and we had planned to move the male, but do you think i should leave him and just plant lots of plants? the female is about 7cm and the male about 5cm and the tank is maybe 40cm by 20cm. im thinking we may need a bigger tank now. also what do i feed the juvenile yabbys when they leve their mother?
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Kalista 6 November, 2011 21:51
I have roughly about twenty yabbies in an old bath tub. I don't have a filter in it because I haven't got around to it yet. I do have some of those drops that filters the chlorine and such out of the water. But, until I get a proper filter, how often do you think I should clean the tank manually?
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Trini 8 November, 2011 20:28
my yabbie was pregnant and the eggs were shinny and black, i went on holidays for 6 days then ther was no sign of the babies. What happend
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Discovery Centre 11 November, 2011 12:10

Hi Trini,

Even though yabbies lay hundreds of eggs they may not all hatch.  If you have only one female yabby, and no male, the eggs would not be fertile and the yabby most likely ate them. Yabbies often eat their young.  For further information, visit the NSW Department of Primary Industry website, which provides useful information on keeping yabbies, their reproduction and their diet.

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Nicholas 19 November, 2011 22:08
My yabby has shed its skin. But it has no claws and only 4 legs. What should I do
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Discovery Centre 21 November, 2011 15:51

Nicholas - when a yabby loses its claws or legs, they will start growing back the next time it moults. If the yabby is young and the claw or leg is small, it may grow back completely during a single moult. Most of the time, however, three or four moults are required to fully restore the limb.

In the meantime, your yabby may need to be offered a diet that it can easily consume without the need of claws. Just to make life a bit easier for it. The more the yabby eats, and the warmer the temperature of the water (up to 26 degrees), the sooner it will moult and the quicker its claws and legs will return.

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Destiny and Chloe 30 November, 2011 10:06
well me and chloe have yabbys and i have 1 and my freind chloe has 364 so email me if u want to no someing and ill tell u everything u want to no
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destiny and chloe 30 November, 2011 13:42
how can you tell if there a boy or girl and also how big can yabbys get
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Discovery Centre 30 November, 2011 16:05
Hi Destiny and Chloe, if you scroll to the top of this information sheet you will find that is about how to tell if your yabby is a boy or girl, so you will find the answer there. The yabby Cherax destructor can attain a total length of around 16cms. 
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destiny 1 December, 2011 09:36
hi its me agin well just woundering if you can put a female and female and male and male can go in a tank together and if the mum is aloud to go in with her babys
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chloe 1 December, 2011 09:40
how many eggs can they have
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Discovery Centre 1 December, 2011 10:55

Hi Chloe,

Female yabbies produce 100 to 500 eggs per individual, depending upon their size. You can find more information about yabbies on the Department of Primary Industries website.

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Catherine 12 December, 2011 13:22
Hi, I've just gotten three pet yabbies and am a bit worried about the smallest one (Bill). He seems to be losing the use of his legs and falls onto his back every now and then. Is it possible this is just part of the moulting process, or is poor Bill dying already? Thanks, Catherine
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Catherine 20 December, 2011 10:34
Poor Bill died the other night. I think he might have injured himself trying to move a piece of driftwood as I found a leg attached when I moved it. I hope the other two don't have similar accidents.
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Discovery Centre 30 December, 2011 13:06

Hi Catherine.

We forwarded your question about Bill to Museum Victoria's animal keepers, and they provided us with the following answer:

There are a number of causes that would explain the behaviour of Bill. The most likely is that he’s having trouble moulting, as this is the period when yabbies are most vulnerable and when the death rate is highest. Yabbies lose the ability to move around during the moulting process and at this time a yabby will often be seen lying on its back or its side. However, moulting should take no more than 20 minutes, so if the yabby continues to behave in this way, it may be stuck in its old skin.

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kelly 4 January, 2012 23:28
I have 8 baby yabbies (about 2 weeks old) and was wondering how big the tank should be and what I can use other than tubing for hiding places. Is 8 too many to keep in the same tank? Ive heard that they need a calcium supplement, is that necessary? Any other tips on raising baby yabbies would be greatly appreciated.
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Megan 10 January, 2012 22:26
Hey guys. I have a Yabbie and the shopkeeper couldn't identify it's sex. it's turning it's tail up like it's laying eggs but i haven't seen any? does this just mean they arent big yet or is it just something some yabbies do? i was going to pick her up and have a better look but i dont want to put her under any stress.
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Discovery Centre 12 January, 2012 16:16

Hi Megan,

The information above should be able to assist you identify the sex of your yabby. Eggs will be produced if the yabby is a female and the water temperature and other conditions allow it. If you believe your yabby is producing eggs, and there has been no contact with a male yabby, the eggs will not develop and they will most likely be eaten. In regards to the curling of the abdomen, this may indicate that the female is readying herself to reproduce. However there could be a variety of other reasons for this too.

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Josh 14 January, 2012 15:14
Hi all, I have a 4ft tank with 4 adult yabbies & roughly 15 small/medium babies. My favourite 'Bruce' who was electric blue died last month for no apparent reason.. This morning 'Big Mumma' suddely died also. I'm worried there's some disease in the tank because Big Mumma had little brown dots on her claws where shell has been eaten away or was maybe rotting? Havnt heard of anything like this before, can anyone help me out? Bruce was only a year or 2 old, Big Mumma was a wild catch but was rather large so I'd guess she was old.. In the tank the little guys all seem really active but the adults are always hiding away in logs and seldom move. Cheers
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Ash 16 January, 2012 14:39
Wow the yabbies in my dam are massive we've got fish in there and every time i chuck ayabby net in there are no small ones. oh and how big of a tank should i have for my yabbies?
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Leanne 27 January, 2012 22:52
We have 5 yabbies in our tank and we cleaned the tank out the other day for them but when they were transferred into a bucket 1 yabbie bit our other yabbies main claw off :( I fed them worms today and my one claw yabbie couldn't seem to eat :( I'm worried about him, what do I feed him if he can't pick his food up and will he survive!! Please help
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Discovery Centre 29 January, 2012 16:24

Hi Leanne, yabbies are well adapted to feeding with only one claw and even with no claws. They use their claws to defend themselves, to capture living prey and to tear food apart. Your yabby shouldn't have too many problems feeding, other than the fact that it won't be able to tear up its food, so it will only be able to cope with smaller portions. You may want to pay extra attention to feeding it small portions, but even so there are generally enough small pieces of food in an average tank for it to get by. It will also be more vulnerable to attack from other yabbies now, so make sure there are plenty of hiding places in the tank.

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megan 7 February, 2012 22:16
hi can i please get some info about one of my yabbies? i have noticed my yabbie is laying on the side some of the time and holding the tail in under the body and i never see the tail out at the moment. is this because it has eggs (i havent seen any) or is there another reasion this is happening
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Izabella 12 February, 2012 23:28
I have a yabbie from 'the wild' and placed in a approx 31cm x 61 cm tank. I am pretty sure it's a male. I am thinking of introducing a similar size female into the tank. My concern is that if they reproduce, what happens to the large number of skins from malting jouveniles which apparently they can do every few days to start with - won't that much waste contaminate the water? I think that being able to see the whole circle of life would be quite interesting but what do I do with all the young? How do I keep the tank adequately clean? How do I make sure that when one of the parent yabbies malts, it doesn't get injured by the other? Lastly, can a single male yabbie be perfectly happy in his tank on his own - for good? I would really appreciate some feedback on my concerns.
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Sam 28 February, 2012 19:44
hi there, i have 4 yabbies, one i have had for 12 years and he was fully grown when i caught him, he has only grown maybe 4cm in 12 years and hasn't moulted he's shell in about 3 years. he is about 20cm long and in a 50cm tank, is it possible he cannot moult anymore because he needs a bigger tank? also I'm going to get a bigger tank and put a couple of my smaller yabbies (10cm) in with him, will he just dominate and kill them or should i get another one closer to he's size? but also i don't want him to be attacked because he's so old I've had him for so long...thanks very much fr the help!!
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Discovery Centre 4 March, 2012 14:16
Hi Sam, Yabbies moult throughout their lives, but as they get older and bigger the frequency of moulting declines. So what you're experiencing is not unusual for an old yabby, and it would be the case regardless of the size of the tank.

When more than one yabby is held in a tank, there does tend to be aggression and the bigger yabby will almost always attack and dismember any smaller ones. We don't think the older yabby is at risk from the younger ones, even if there are a number of them.

The risk of aggressive encounters is greatly reduced by giving the yabbies places to hide, and with the right set-up a number of yabbies can live together for many years. Many yabby keepers use strips of corrugated plastic sheeting, layered on top of each other at the back of the tank, to form a kind of apartment block with dozens of small rooms that are more easily defendable by each occupant.

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Max Leonard 17 April, 2012 15:22
Hi, I have a yabby but i am not quite sure if it is a boy or a girl so can you send me a picture of a girl and a boy.
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zak 19 April, 2012 22:43
hi i just got another yabby today and is has no nippers its whole arm has come but it came like that both of them wernt there who long it take for them to grow back it os about 7cm its still young. thank you
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Huseyin 21 April, 2012 21:31
Hi I have about 30 yabbies approx 5cm in lenghth in a standard 4 feet fish tank. Is that size aquarium ok to house them. I feed them sinking vegetable pellets that are used for bristle nose cat fish. I'm also wondering if they eat frozen Turtle food, Brine shrimp, Bloodworms. Also at what size can you sex Yabbies. I have heard that they need a calcium supplement, is that necessary? Any other tips on raising baby yabbies would be greatly appreciated.
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Discovery Centre 22 April, 2012 11:23
Hi Zak, Moulting occurs frequently when the yabby is young, as often as every 10 days. Older yabbies will moult only every couple of months. If a yabby is missing a claw or two, all its energy will go into regrowing those claws, at the expense of overall growth, so the yabby's increase in size will be much slower. But if the yabby is young enough, both claws may reach full size by the time it becomes adult. Keeping the yabby slightly warmer with plenty of food will encourage it to grow more quickly.
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brodie 22 April, 2012 20:20
Hi, Im going to farm them but i am not quite sure if it is a boy or a girl so can you send me a picture of a girl and a boy
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Huseyin 23 April, 2012 13:04
Minim just wondering when yabbies molt do they give of any sent or something to say they are molting. Which in turn makes them vulnerable to be attacked.
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Discovery Centre 25 April, 2012 10:12
Hi Brodie, there is a fantastic illustration above that shows you the difference between a male and female yabby, hope that helps!
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Elanor 26 April, 2012 15:18
Hello, about the hiding places for yabbies, should they have an escape route out the back or be closed? I have 2 small yabbys in a 70L tank and all my hiding places are more like tunnels than caves. I was thinking I should get stuff more like caves, but am worried about one getting cornered. Thanks for any help
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Discovery Centre 27 April, 2012 15:25
Hi Elanor,
We asked our live animal keepers for some advice:
In the wild, yabbies dig burrows that are open at the entrance and closed at the other end, which is how they feel most comfortable. With the claws at the front of the body, yabbies are designed to defend these burrows and as a general rule have no problem doing so, but are not designed to defend themselves from behind. An opening at the back makes them feel vulnerable from a rear echelon assault. The best option, therefore, is to give them a cave-like shelter rather than a tunnel.
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Discovery Centre 3 May, 2012 12:24
Hi Huseyin, we have checked with the Live Exhibits Team about molting yabbies and yabbies, like all arthropods, produce a moulting hormone that causes nutrients etc from the old skin to be reabsorbed into the body as the skin separates. This is an internal hormone and it’s not known whether any is released into the water, or whether predators are able to pick up on it. It would be in the yabby’s interest to contain the hormone, but it’s a very good question and would make an interesting research project!
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Huseyin 4 May, 2012 13:33
Hi I have about 30 yabbies approx 5cm in lenghth in a standard 4 feet fish tank. Is that size aquarium ok to house them. I feed them sinking vegetable pellets that are used for bristle nose cat fish. I'm also wondering if they eat frozen Turtle food, Brine shrimp, Bloodworms. Also at what size can you sex Yabbies. I have heard that they need a calcium supplement, is that necessary? Any other tips on raising baby yabbies would be greatly appreciated.
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Discovery Centre 27 May, 2012 16:02

Hi Huseyin, 
We forwarded your enquiry to Museum Victoria’s Live Exhibits team, the Museum’s animal keepers, who responded with the following information:

A standard four foot (120cm) tank will house about eight full sized yabbies or approximately 30-35 yabbies of the size you describe. So your tank is suitable at the moment, but will need to increase in size as the yabbies do (or you'll need to downsize your yabby collection). You can keep higher numbers of yabbies together if they all have suitable hiding places.

Yabbies are basically carnivores but will feed on any organic material available. High protein pellets are better than vegetable-based varieties, as yabbies will always choose meat-based food over anything else, and they will always breed better on a higher protein diet. Special yabby pellets are available from some pet shops or directly from RBM Aquaculture (http://www.rbmaqua.com.au/).

Earthworms, brine shrimp and bloodworms are all good food items, as well as fruit and vegetables such as carrots, spinach, potatoes, peas, apple and peach. Although they do favour meat, variety is very important to them and it is also important that the food offered is fresh. Don't overfeed them as the food may go off and foul the water (it's always safer to underfeed, if anything) - one pellet per yabby every second day plus a small earthworm and a piece of fruit per yabby per week is a good guide.

Calcium is important for a strong exoskeleton, and can be provided by washed sea shells or pieces of coral from the beach, or from calcium blocks available in pet shops.

Adults or yabbies approaching adulthood can be sexed by looking underneath - males have a small projection at the bases of the fourth pair of walking legs, whereas females have a small round patch on the bases of the third pair of walking legs. In general, males are larger than females and have larger claws, with a more narrow tail, and this applies throughout their development.

Ben 25 June, 2012 19:05
Hi I had 5 Yabbies and 4 died and the remaining one ate most of the rest dead bodies. It is now alone and I am not shore about the gender. Also can Yabbies get lonely I feel a bit sad for it
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Amanda 21 July, 2012 12:25
Hi this forum is great I have learnt a lot as we have quite a few yabbies in a big tank but I have noticed last night and today that one of the more dominant yabbies in the tank is sitting on top of a more vulnerable one, at first I thought they were breeding but now Im not sure. I saw in this forum that a dominant yabby could slowly dismember another one and Im afraid that might be what is happening as the vulnerable yabby has only one nipper and has lost a couple of legs.
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Discovery Centre 24 July, 2012 17:03

Hi Amanda; we've checked with our Live Exhibits team, and they have the following response for you:

If a dominant yabby is allowed constant access to a more vulnerable one, the dominant yabby may slowly dismember it until it has no legs or nippers left. It could be a case of not enough hiding spots – in most situations any yabby can protect itself from any other as long as there are enough places to hide. If there are enough hiding places but you’re still concerned, the only other option is to give them two separate tanks

Hope this helps!

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Harrison 24 July, 2012 22:16
Hey I'm just wondering I've had my pet yabby for about one year and I've never seen it shed but I'm out of the house 1 week of every fort night and he's just eaten it and I haven't noticed. When I caught him he only had half of his legs and 1 claw and he's fully formed again. AND sorry to be a pain but I'm not sure if my tanks big enough to get him a friend could you plz let me know like how wide and long it has to be all I can tell you is it has a filter, pebbles on the base and a hiding place for my current yabby (pinchy) yes I know real original
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Harrison 25 July, 2012 22:30
Hey sorry bout last question it doesn't really make sense so... How wide and long should my tank be for 2 yabbys to live in
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Rhys 20 August, 2012 21:07
Hey Discovery, I have 2 yabbies (yabbos and brutus)in a pretty small tank and recently they have started fighting and early thid morning i noticed that they have been curling the tails tightly(both of them) would could be wrong?
Discovery Centre 21 August, 2012 16:53

Hi Rhys - we've passed your question on to our Live Exhibits team here at the Museum, and they have prepared the following response for you:

If the yabbies are in a small tank they will certainly have started fighting due to lack of space. If one of the yabbies is dominant it will rapidly pull the legs and nippers off the other yabby, and if they are evenly matched they may pull each other’s legs off over a longer period of time. The first thing to do is to give them more hiding places, using PVC piping or layered strips of corrugated plastic, or some more natural arrangement. There should be at least 10 suitable places to hide within the tank. The next step is to give them a bigger tank if the extra hiding places don’t do the trick.

Hope this helps!

hailey 9 January, 2013 16:16
I have 3 yabbies ina medium sized tank and one of them attacked a smaller one that had just moulted. Because of this it has now lost both its claws, those limbs that help it find food and have two legs left. I moved it to a different tank and right now its still alive. HELP!!! I don't know how old it is, but its the size when you open up your index finger and middle finger. It won't eat. It has also lost an antennae.
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Discovery Centre 12 January, 2013 12:22

Hi Hailey, we have checked with our Live Exhibits Team and whenever more than one yabby is present in a tank, the larger one(s) will attack the smaller one(s), even if the size difference is minimal. And once the attacks begin, they will continue until the smaller yabby(s) are in pieces. The only way to avoid this is to provide plenty of places to hide, so that the larger yabbies don’t feel their territory is being encroached upon, and the smaller yabbies have a handy retreat. Hides can include empty plant pots, PVC pipes or any suitably sized object. Breeders with many yabbies place layered pieces of corrugated plastic sheeting inside the tank to provide dozens of hiding places.  We hope this helps with the care of your yabbies.

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Natalie 13 February, 2013 09:09
In my dam, there seems to be a few different varieties of Yabbies. A blue pearl, all black/blue, all beige and all beige with red claws. I would like to catch a breeding pair to put into a tank. Should I try to catch a male and female that look the same colour, or are they not that fussy?
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Jamie 15 March, 2013 23:08
Hey I have some blue claw yabbies in a tank and I want to put some blue maroon yabbies in with them but I was told that the blue claws will kill them so I was wondering if there were other kinds of yabbies that you could put with the blue maroons or if you could put bigger blue maroons in with smaller blue claws Thanks
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Lana 11 April, 2013 18:21
we have a blue yabbie and he has been, well normal, but the past two weeks, he is extremely active, pushing all his rocks to one side of the tank, filling up the filter, going under the filter pushing it up, standing up on his tail and putting his pinchers out of the water and just being a little agressive. He has moulted once since we have had him (about a year, and he shed about six months ago) is he just being abnormal, or could he be shedding again(im guessing he is a He, dont know the sex)
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Discovery Centre 23 April, 2013 13:09

Hi Lana,

Although yabbies tend to hide in crevices and holes most of the time, they will generally leave their hiding places to moult, presumably needing an open space to manoeuvre out of the old shell. Your yabby may have decided the tank needs rearranging before this task can be undertaken. Moulting takes place at irregular intervals, depending on the conditions and the amount of food available, and reduces in frequency as the yabby grows. Young yabbies may moult up to five times per year, whereas older ones will moult once every two years, and males tend to moult more often than females. There is plenty of information on the internet on sexing yabbies, including Melbourne Museum's website 'Is my yabby a boy or a girl'

Emma 14 April, 2013 13:57
Hi, I recently noticed that my yabby has not eaten any of the food I've put in and his claws have a orange film covering them. Is this just because its winter and they dont eat and move in winter? or is he sick? I cant find ANYTHING on the net to explain
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Discovery Centre 23 April, 2013 12:44

Hi Emma,

In the wild, yabbies dig into the banks of a pond during winter and become inactive - you generally won't find yabbies during any month without an 'R' in it. In addition, yabbies will not feed if the water temperature is below 10 degrees Celsius, and won't grow below about 15 degrees. Room temperature is usually above 10 degrees even if unheated, so it may be that your yabby is simply slowing down and not feeding as often. If you're leaving food in the tank, the excess nutrient may explain the orange film covering the yabby's claws. The best option is to reduce the quantity of food offered and remove excess food from the tank if not eaten within a day.

Pete 4 July, 2013 17:54
Hi All, I'm relatively new to the world of pet yabbies. Recently I thought I'd give my 5 foot aquarium a new lease of life by adding some yabbies from my parents-in-laws dam. (it used to be the home of my pet turtle which we had for many years) Both myself and the kids find them fascinating to watch. They've got plenty of places to hide and seem pretty active and happy. Recently however, both the males & females have been climbing up some of the rocks & standing on their back legs to lift their upper bodies out of the water. They then extend their claws upward and begin to shake from side to side for several seconds, sometimes repeating the process several times. While it's highly amusing to watch, and almost looks like some sort of crazy dance, I wanted to make sure it's not an indication of illness or something sinister? As I mentioned, they otherwise seem very happy & healthy. Any insight would be greatly appreciated.
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Discovery Centre 7 July, 2013 10:05

Hi Pete, wild-collected yabbies, particularly adult yabbies, will constantly try to return to their original pond when translocated to an aquarium. They appear to have good memories and a surprisingly good sense of direction, and will spend much of their time trying to escape, particularly at night. Young yabbies, or yabbies produced by an aquaculture farm, tend not to show this behaviour as much. Having said that, yabbies of any type are inveterate explorers and escape artists. They will climb up air hoses, rocks, logs and any other object in the tank, and squeeze through the smallest opening to go on their way. All yabbies demonstrate this behaviour, which is why they are so widespread in the wild and why they quickly colonise any new dams under their own steam.

Pete 18 July, 2013 20:23
Thanks for the response! I don't think they are trying to escape the tank when they do this. They simply climb up on some of the shallower rocks, do this "dance", occasionally blow some bubbles, and then go back to doing what yabbies do. Anyway, they are still all alive so I don't think it's anything sinister. We have 12 yabbies of varying sizes, and some of the females are starting to come into berry so it's all getting pretty interesting! Thanks Again, Pete
mike 14 September, 2013 06:04
i have one blue yabbie iv had it from a baby with no outher yabbie it has eggs now for the seckond time will they hatch or do they lay fake eggs like some lizards like the chameleon
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katrina 21 September, 2013 20:46
Very new to the whole yabbie pet/breeding world , would just like to say this site has helped me sooooooo much thankyou yabbie people and discovery centre
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Josh 2 January, 2014 16:49
Hey there I just recently got myself 4 small yabbies ranging in size the largest is approx 5cm long. I have set up some river rock caves in each side of my tank with General aquairam stone as a base. The have all gone into their corners and pushed most of the stone out. The smallest of the lot has decided to clame the little castle in the center of the tank as it's own. Apart from all of that they do not move from there own spots. Could this be because they are new to the tank, I have to many in the tank (2fX1fX1f aprox), or is there some other reason? Thanking you in advance.
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Tristan 23 January, 2014 02:32
Hey i have two questions if anyone could answer, i recently bought yabbies and I'm not really bothered if they're male or female but one of them is continuously hot its tail curled up, does this mean that its baring eggs, and also when the baby yabbies hatch is it ok to separate them from the older yabbies to insure survival of them?
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Kev 9 April, 2014 12:25
Thank you for this information but I am left somewhat confused. You advise above that the female reproductive openings (or gonopores) are on the third - or middle pair of legs - further illustrated by the RHS of the diagram. Why then does it go on to advise to look for her genital openings on the SECOND walking legs while in berry? (last paragraph of this webpage: http://museumvictoria.com.au/discoverycentre/infosheets/is-my-yabby-a-boy-or-a-girl/ ). Is there perhaps FOUR genital openings - or is a genital opening on the third pair of legs an intersex type indicator - as the former reference to the SECOND pair of legs is whilst in berry (albeit grape-like berries are not in the illustration it refers to)...
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Discovery Centre 28 April, 2014 11:57
Hi Kev - Yabbies have 14 pairs of appendages under the body, which are divided up into different groups, and modified according to their functions. The first three are feeding appendages, the next pair are the claws, and the next four pairs are walking legs. The confusion here is that the second pair of walking legs are also called the third pair of pereopods (the first pair being the claws). Taxonomic nomenclature can be confusing, but if you read the page carefully you'll see the distinction.
Kate Wilson 8 September, 2014 13:38
Hi there, I have 1 female (very aggressive!) tabby in a filtered tank. I went to clean the tank. She always tides in a cave -I pulled the cave up and she fell out the bottom (as always) but I saw that both of her claws have fallen off from the body! we have had her for over 2 years - help!
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Discovery Centre 14 September, 2014 09:34
Hi Kate, there are three reasons that yabbies (Cherax destructor) drop claws. The first is fighting between two yabbies where the larger individual will cut off the limbs of the smaller individual. The second reason occurs when the claws are caught in or under an object, and the yabby drops them to get away. The third is poor environmental conditions, although this is less common. Check that the size of the tank is appropriate for the size of the yabby, make sure the water is filtered and aerated, the temperature is adequate and the diet is suitable.