Backyard Aquaponics
A place to discuss aquaponics

new batch of Barramundi have been in tank for 2-3 weeks. (PH7.1)
36 x 300gm dead in morning. The two survivors were the smallest.

The interesting thing (to us) was the way they died. ALL ON THE FLOOR OF THE TANK , ON THEIR BACKS.
their mouths were open, their gills were clean (very healthy looking). THEY LOOKED AS 'THO THEY HAD DIED RIGHT WHERE THEY WERE 'SLEEPING'- SIDE BY SIDE BY SIDE-IN TWO OR THREE DIFFERENT GROUPS.

Your thoughts would be appreciated - thanks !

i've never had barra,,, but what are you temps?

what are your other readings (am, nitrites and nitrates)?

Also, what is the size of your tank? How is the clarity of the water? Is there a smell? I agree, check your nitrogen readings.

I recently had an ammonia incident in a new tank. I thought it was cycled 'well enough' for the bio-load. I -should- know better and I think sometimes you forget the little things. I ended up losing all 20 of my fish

Going to need lots more info for us to be of any help. What are your system specs and how old is it etc etc. Pics would help too...

Ammonia level spike, How much air was going into the tank. The larger fish die first then the smaller ones.
Suspect your pump shut down and no water circulation caused ammonia to rise and lack of oxygen. Have you a photo???? if not use mine. Should look the same.

Thing is to move on, It may be the first but certainly wont be the last time this happens. With mine they only had another week left in that tank. Still have another 20-25 the same size in another tank. Both tanks were hooked in parrallel (IBC's) One had 50+ fish in it and the other 20.
So the lesson learned is not to over stock the tank just in case.

Thank you, all !
"Chainsaw" - Thank you for the photos. (we didn't think to take any ).
It certainly seems to be similar. We will check along those lines.
LOVE THE ENCOURAGEMENT TO CONTINUE ...thanks !

If you haven't already, you should buy a freshwater master test kit (ammonia, nitrite, nitrate, pH) or at the very least an ammonia test kit.

That way you can regularly test your water parameters and identify any spikes before they lead to losses (unless of course it's related to hardware failure). The master kit will also be informative as to whether your biological filtration is functioning correctly, as this can be disrupted by a host of different actions, like a >50% water change or adding chlorinated water straight from the tap.

How long has the system been running for? The barra have been in for 2-3 weeks, so had the system cycled before you added fish? How many fish in how many litres of FT?

It is summer, and temperatures are warming up all over. I would suspect insufficient aeration (oxygen). The warmer the water, the less dissolved oxygen is in the water. Worst still if you have healthy bacteria colony, as converting ammonia to nitrate requires oxygen, so the filtration is competing for oxygen with the fishes.