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Oct 03

Baby Yabbies

When she got pregnant, it was time to rename “Marsellus” to get her gender correct. One of our yabbies got laid a few weeks ago, and right now she’s packing hundreds of baby yabbies underneath her tail. It’s quite a repulsive sight actually, but I’m sure once the yabbies mature they will be a bit cuter.

Pregnant Yabby
The piece of shell in the picture is a leftover from a recent moult
(or more accurately, a recent occurrence of ecdysis)

I went scouring for a bit more information about Yabby breeding habits, since I’ve heard that yabbies eat anything, and that anything includes their young. And if they don’t eat their young, then we still have a slight problem if nearly 100 baby yabbies are roaming around the tank.

PDF Datasheet

Yabby FAQ

When freshwater crayfish mate, the male deposits a small packet of sperm gel on the female, near the reproductive openings. The female then passes the eggs out through the openings and across the sperm packet, during which process they become fertilised. The eggs are guided to the underside of the tail (kept cupped during egg laying), where they are fastened on to the swimmerettes (the small legs on the abdomen) and carried until they hatch. Juveniles have special hooks on their legs to allow them to cling to the hairs of the female’s swimmerettes; they moult several times before leaving the parent.

The female protects the eggs carefully. If the level of dissolved oxygen falls, she elevates her tail and fans the eggs. If the water becomes too warm, she will find a cooler place. However, because the eggs are large, and because of the time and energy she devotes to them, she can afford to produce only a few hundred compared with the hundreds of thousands of relatively minute eggs of the marine lobsters. The newly hatched young are known as ‘juveniles’; they resemble the adults and do not pass through the free-living larval stages of lobsters, prawns and many other crustaceans. The juvenile yabby is consequently better equipped for survival than the young of most of the marine crustaceans and not as vulnerable to predation.

Breeding begins in spring when the water temperature reaches 15 to 16*C. The first batch of eggs (100 to 500 eggs per individual, depending upon the size of the female) hatches 8 to 10 weeks later in early summer. As soon as the young have left (a further 3 weeks later), the female is ready to breed again. Because of the higher water temperatures in summer, the second brood takes only 3 to 4 weeks to incubate. Some females will breed three or more times during the breeding season [oh shit], which, if the temperature remains high enough, can extend into autumn. In the warmer water in the west of the State, the breeding season may continue almost year around. … The yabby is not averse to attacking and eating its own kind, especially when the prey is smaller, or soft after moulting. (Src)

In courtship the male yabby uses his claws to impress the female. After mating the male has no interest at all in the upbringing of the young yabbies. The eggs which have been fertilised lies between the females rear legs so she curls her tail around them to cover them. Hundreds are laid at a time though not all hatch. After birth the young hang onto their mother for 4 to 6 weeks At this stage they are known as “Larvae”. (Src)

i have been raising yabbies for about a year and a half now, and everything has been going really well. in fact, 3 weeks after introducing a new female into the tank with my big male, she got pregnant. unfortunately i have not had another tank spare to move the female and the young ones to, and now i have around 70 to 100 baby yabbies roaming the tank. a problem has arisen from this, however, as i had an internal power filter running on the tank, but the babies were being sucked into the filter and i have taken it out. this leaves me with no filtration and no aeration, which brings me to my point. has anyone got any suggestions on how i might go about aerating the water? (Src)

Hmm. Yes, the aquarium’s going to be interesting over the next few weeks.