Backyard Aquaponics
A place to discuss aquaponics

Hi all,

I brought a bucket of yabbies home two weeks ago, caught in a relative's dam. The thought was that they might go in my new AP system. As the system wasn't up and running at that stage, I set up an aquarium filled with rainwater and a couple of air stones, and some PVC pipe off-cuts for them to hide in.

As of last Friday, only two yabbies had survived in the aquarium - I put this down to the extreme heat we've been having (44+ deg C) as the aquarium was set up outside. One of the remaining survivors looked near death and was barely moving when I placed them both in the new AP system on Friday. As of Saturday, the near-death one had died but the other was still alive & walking around, but then I think it died on Sunday. Water temps in the system have not exceeded 28 deg C.

Any thoughts? I'm kinda hoping that whatever killed the others in the aquarium is the same as what killed this one in the main system, and that there isn't something horribly wrong with my system...

Think you're right about the heat Jimmy.... I've been finding one or two a day dead over the last week or so... water temp 28+....

even my local news here in Florida was speaking about the extreme temps you guys were getting in Adelaide

im sorry to hear you are losing stock

Sadly Johnnie... also 22 human lives been lost due to the heatwave...

Yep, I've been loosing quite a few as well. 28 degree water shouldn't be an issue, most references suggest that yabbies will survive up to low to mid 30s. High temperature plus the shock of being moved might account for the deaths. At least that is what I am putting mine down to.

Like most things jimmy they can tolerate high temps for a day or so but with the continued heat it eventually gets the better of them. More air is needed with the temps but pumping hot air through the water seems to heat it up more.

I'm in Adelaide also and my garden looks like someone has been at it with a flame thrower. I have covered all my plants with sheets but anything planted in dirt will be lucky to see the week out . AP stuff in shade and doing ok.
Fish tank is at 32 and has been as high as 33 and not below 29 even at night) in over a week. My silvers are munching eating each others tails even after i have doubled their feeding, they are in total overdrive.

Okay, I'm reassured (kind of) that the deaths can be explained by shock of moving and heat and I will hope like hell that it isn't some horrible contaminant in the system. Given that most of the deaths occurred in the aquarium I think this is a reasonable conclusion at this stage. I'm not massively concerned about the loss of stock (we're only talking about 6 or 7 yabbies) - I'm just annoyed we didn't just cook them up and eat them when we had the chance!!!

Still, when it comes to stocking the system properly I will tread carefully and will perhaps start with a handful goldfish and see whether there is further attrition.

also with high heat and low rainfall. you also get the fires im hearing about.

are they nearby to you jimmy?

No, they're nowhere near me - touch wood! Certainly we have the high heat and low rainfall here though.

i have had yabbies die on me as well 1st attempt at an AP yabbie system. (2 days dead)
attempt 2 put in air stone a little better (1 week) i concluded it was a combination of water quality and not enough air in the system attempt 3 good clean water plenty of air and 1 month and 3 days still going

It's really strange, I've dug live yabbies out of the mud in a dry creek-bed in the middle of summer, and all the aquaculture information seems to suggest they can survive in stagnant water with near-zero oxygen and up to 35 degrees water temperature - you'd almost think the aquaponics water would be too nice for them, if anything! Makes me think they may be ultra sensitive to something else that we're missing.

You haven't got any copper near them, or in the water tying something up have you?
Any additives that contain copper could do it too.

Yikes - actually I have tied up my float-valve using copper electrical wire (seemed like a good idea at the time). I think the yabby had died (or was nearly dead) before I installed this but I will remove it asap. It's insulated so there is minimal contact between copper and water, but still I'll replace it with something else.

I think the float valve has a brass lever on it - do you think that would be a problem (from memory brass is partly copper)?

If it has gone green then maybe but if there is no sign of corrosion then i would have thought it was ok. Anyone else?

maybe ask your question to Crusty on the crayfishmates forum:
http://www.crayfishmates.com

frank