Backyard Aquaponics
A place to discuss aquaponics

I have had my setup for around 3 years. Throughout this time I only had one random fish death ages ago.

The fish have grown from fingerlings to about 20cm. They are Silver Perch.

Yesterday I noticed they were all swimming at the top of the tank which was unusual.
I fed them, they became active and ate.
Everything seemed fine with the tank and setup.

24 hours later, they are all at the bottom of the tank dead.

Nothing has changed in the tank setup.
There were a string of 40c+ days, but this is no different from previous summers.

I don't know what happened, was it just the heat?

How hot did your water get?
It may have been too hot, leading to low dissolved Oxygen levels.

Oh no bad luck
Dead fish are no fun
Probably too hot and low oxygen as Gunna posted
Cruising the top of water would indicate searching for more oxygen

Do you have your system shaded

Doesn't help you now but I find running constant flood during the day and siphon at night saves me about 2 degrees.

And if I start this a couple of days before the heat wave its even better .

A couple of years ago I had Silvers and we had a prolonged heat wave (Riverland SA) my water got to 36 and I was getting pretty worried but got through ok , ended up losing them mid winter (too cold ) big learning curves in aquaponics.

Ive read nothing survives 40c

We have had a couple of runs of heat waves , my systems have been getting to 30 / 31 by the evening
I have Murray Cod and I don't know how heat tolerant they are .
Last couple of days there feeding has dropped off , we had a good cool change 16c overnight fish tank is down to 25c and they are back to smashing their feed , so I don't know if I should be watching this as a red flag or not .
Its certainly got me thinking.

Check your pH. When I noticed silvers swimming around near the top the pH would often be very low, not that this should have killed them over night. Spray drift? I remember someone losing their fish after a neighbours termite spraying.

Seems strange, it has been warm to hot, but not what I would call excessive.

My silvers which are probably a similar size, are doing fine after the hot spell we had.

Have you checked the water,just to rule it out?.Especially Ammonia.

I figured there was no point checking the water quality after every fish had died. The dead fish would have been enough to mess up the quality regardless.
I am currently draining it so I can restart.



It's on a side fence next to a road.
It is unlikely but possible spray from council workers came over. They would have to get it quite high and I haven't seen any council workers around.



Not sure. I need to get my Raspberry Pi monitoring system finished to I can monitor it better.



It is shaded.


The water has gone oily now and stinks of fish. I missed a couple when cleaning out the dead ones. I think they are all gone now. Regardless, I am draining it.
Is there anything I should sterilise it with, which is fish safe, before refilling?
I was thinking of just leaving it empty for a few days using the coming heatwave to kill anything but I am not sure if that is enough.

A couple of good rinses should be enough, fill it up with water, start pumping and monitor ammonia and nitrites before you add more fish. Presumably the nitrifying bacteria should still be in your GBs, so you should be up and running soon. Just don't let the bacteria dry out and cook in the heat.
Scoop out any excess oil that appears on the water, no doubt there is some in the GBs.

Every body i know in aquaponics has at least 1 decent fish kill even the commercial growers

Maybe a PH crash?.KH?