Aquaponics - Yabbies!

I just raised some baby yabbies. Yabbies are a freshwater crayfish that call Australia home.

Which is nice.

So now I have to farm them.

Tricky.

Yabbies are so delicious that they tend to eat each other.

Yum!

Tricky.

The problem is they they each want a stack of space to call their own.

They also take their time growing, but I just found this from...

http://www.fish.wa.gov.au/Documents/aquaculture_yabbies/how_to_grow_bigger_yabbies.pdf

"Separating males and females by hand is time-consuming and prone to mistakes. To make this
easier and more accurate, a hybrid has been discovered that only produces male progeny (by
crossing male WA yabbies Cherax albidus with female Cherax rotundus yabbies from NSW)"

According to the Western Australian Government fishy people, "Monosex culture provides a 70 per cent increase in gross return to the farmer."

I've had my first batch of yabbies drop from their mother, so I'm now a little obsessed with high stocking rates. I have the entire clutch in a very small 30 litre tank. So far they don't seem to be hurting each other, but they are very vulnerable when they shed their crunchy outer shell to make room for the next bit of growing they plan on doing. Shedding your armour also turns your pincers into mushy things that are no good for pincing.

No good at all.

I put the berried (that's what we yabby farmers call yabbies with eggs stuck to their undersides) female in a cage made of gutter guard (a plastic mesh to keep leaves out of your house's gutters) so the delicious babies would fall through and wouldn't get eaten by their mum. It seemed to work. Babies would let go, spend a minute or so near their mother, then drop to the bottom and never return.

For high density raising, I have a bit of a moral problem with battery hen style conditions even though (or perhaps because) I did some work on a design a few years back. But now I have an idea that I think might work for an IBC.

Basically its a 3D zig-zag of shade cloth that works it's way down a container like a staircase...kind of, so that there is a minimum of 5cm and a maximum of 8cm between each level. I'll attach a stack of PVC homes on each level that get larger and fewer as they get to the top. All of them should point downhill a bit so food and waste don't get stuck, and the basic plan is that the bigger you are, the higher you rise in the yabby high-rise (with me being at the very top). There would be gaps around the edges, so the smaller yabbies and babies would be able to find their way down with ease. They can sort it out among themselves as to who gets the housing at the top nearest the biggest food.

Watching my adult yabbies, I see that when they eat they let a lot drop. They leave a lot of crumbs. They make Cookie Monster look like something best described with words like "refined". They are also bottom feeders, and are not opposed to eating a meal that has already made its way through somebody else's digestive tract. Or more than one somebody's digestive tract.

So my hope is that I can add fish feed, or even veggie scraps (yabbies aren't fussy) into the top, and draw nutrient rich waste water that has been munched into very fine particles from the bottom to add to my growbed.


120 Things in 20 years needs to learn stuff. It's been a while.