Backyard Aquaponics
A place to discuss aquaponics

We set up a yabbie pond with an under gravel filter approx 5 months ago. Water quality has been consistently good and we've had some breeding success - at least two separate broods where a few have made it beyond being dinner for the relatives. Unfortunately we've had high losses of adults - we add them in batches of 10 and have lost approx 25% over the last 5 months. Any ideas?


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how big is the pond and how many yabs?

They are probably killing each other, sometimes just moving hides can get one out of place and when he goes to the wrong place he gets murdered,

bit like going to Northbridge!

Thanks slow boat - I did suspect that could be the problem. The ponds about 1000 litres and we're bought 40 yabbies (lost 11) but now have a few youngsters to improve morale. We've got lots of retic off cuts for yabbie apartments - maybe we need more. I'll work on getting a photo up.


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Are they just dying, or are they killing each other?

Hi mr damage - we're not really sure. There's a lot of aggression happening (rod optimistically thinks it's mating). Generally we find one upside down looking a bit worse for wear and a day or two later it's a goner. Water is clear and quality is good. Any suggestions?


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Stock only males in the system. The growth rate will improve and there will be less aggression and cannibalism. Keep a few females in an aquarium etc for breeding.

I agree with MrD, keep single sex ponds until you are ready to breed.

It will provide less opportunity for aggression and territorial issues over females.

When your ready to breed, one male(the biggest) to say four females above 5-7cm.

Are there body parts laying around? or just a full dead Yabbie?

Is the dead yabbie a orangey/yellow in colour? it may indicate a summer malt, and being attacked in their most vulnerable state.

If it is body parts i would say territory.

Mix up the sizes of the pipes your using for hides, so that the larger yabbies cant get to the smaller ones inside, it will give them a safe place.

Regards

Stock about 10 per 1m2 of floor space.

Thanks for all your suggestions. The pond has three tiered waterfall so we might be able to pop the girls in the upper levels and keep the fella's to grow plump in the main pond. Will let you know how we get on. In answer to Porter - occasionally we see a nipper lying around but more commonly it's a full dead yabbie


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Are they soft shelled when you find them dead. When shedding their shells they are very vulnerable to attack

Another thought... what's your pH?... Low pH is not good for yabbies, it really needs to be kept in the high 6's as minimum, preferably low 7's... yabbies will actually prefer it in the high 7's, but your plants won't.

Oh - good thought mrD. This makes more sense cause they seem to lie around wilting for a day or two which doesn't sound like a violent death at the hand(claws) of an aggressive rival. I just tested it and it's quite low. We don't run this water through any grow beds and we've only got a couple of reeds in there so no probs with the plants - I'll have a go to raise it and we'll see how we go.


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if they're not making it through molting.. shellfish need some iodine for shell formation as well.. i use marine aquarium iodide in my crayfish tanks - 1/2 the recommended dosage for marine tanks

I spoke to a crustacean professor at UWA this evening and she suggested shade is what's required - blistering Perth heat is taking its toll. Keith - they all seem to have hard shells when they die - we get plenty of outgrown shells in the pond. Maybe we'll turn the pond into a giant cocktail with lots do crushed ice


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if you don't have shade, the FT will go green with algae.