Backyard Aquaponics
A place to discuss aquaponics

I would guess that your outdoor temps have been pretty cold by now. I know koi are hardy, but I believe temp changes still have to be gradual with them.

What did you do to acclimate the fish to the system?
Were the koi kept inside prior to being moved outside? Do you heat the AP water?

Sorry about your fish!

Were the tilapia raised exclusively in the system, or were they overwintered inside prior to the system water warming enough to sustain them?

They were tilapia from a large outdoor reservoir.

How long did the tilapia last in the system? I think I remember that you may have had a cold snap that killed the tilapia.
The tilapias lasted 2 years. Correct, there was a cold snap and a much more experienced pet shop owner lost all his tilapias around the same time also.


I wonder what the conditions for the koi were like prior to adding them, and what the water temps of the system are.
From the looks of previous pictures, it looks like the system is on a patio outdoors.

The system is fully outdoors. Temperatures were warm but water still cool to the touch. It didn't cross my mind to record the temperature.

I would guess that your outdoor temps have been pretty cold by now. I know koi are hardy, but I believe temp changes still have to be gradual with them.

What did you do to acclimate the fish to the system?
Were the koi kept inside prior to being moved outside? Do you heat the AP water?

The kois were from a good pet shop that gave me a good deal. So they were indoors in an aquarium. In order to acclimatise the fish, I made a water drip siphon from the aquaponics fish tank into the aquarium fish bag until the bag was half full together with adding an air stone in. I then dumped half of that water and repeated the same process. I then added them to my system.

I would guess that acclimating most indoor fish to outdoor culture in your area at this time of the year, might prove to be difficult if the water isn't heated.

How long did the koi last before they died?

The kois lasted 27 days.


I am no fish expert, but might it be possible that they experienced shock from temp change or very cold water temps?

Maybe. I think that temperature changes are likely more sudden in a small barrel system like mine. Two petstore owners were telling me that I shouldn't have lost the tilapias and kois that way as they have seen them in way worse conditions like algae infested ponds with broken filters.

The biofilter might not be very active if the water and outdoor temps are low, and it hasn't had ammonia inputs for a while.
It might not have been ready for the fish load, especially if they were being fed right away.

How was the ammonia level?
What is the ph?

Water parameters were ammonia 0.5ppm,Nitrite 0ppm,pH 6.4 and Nitrate 0ppm

I know it's a lot of questions, but it's where my brain went.....I have been battling with ph crash, and reduced ammonia conversion for a few weeks myself. I gradually raised the ph, and the ammonia has dropped to a more acceptable range.

Hold on a minute...my fish tank and sump tank are sheltered to prevent algae by what I believe are galvanized metal sheets. Zinc toxicity?

I found it take 3 to 4 months depending on the amounts of galvanized metal you have in the system. Also once you remove it you have to do a 100% water change. As far as out side temps I have one system that is outside and am using a a heater system made out of a 230v water Heater probe running at 110v in a 2 in PVC system with a cheap china temp controller. If you look online for aquaponics heaters you will find several ver of this heater. I have used it for two years now and it has worked down to -10 deg and it has maintained 78 to 80 Degs.

I warned you about that on your last post!


Also, what is the total volume of your system?

and is your rainwater top up system automatic, ie., when its raining rainwater constantly enters the system?

If this is the case, parameters (pH, temperature, nitrate) might swing quite suddenly with heavy rain, which would be bad for your fish health as it causes stress even if values are within the tolerance rage. This would be specially bad if the system is relatively small.

+1 on the water change.

I just read through your last post, and was thinking the same thing as Terry.
If they survived for 27 days, it does' seem like an acclimatization issue.

The metal panels could have done it for sure. The age of the panels could influence how much zinc comes off of them.
You could set the same thing up with polycarbonate panels and use the galvanized panels to clad the new IBC!

It is true that a larger water volume will change temp more slowly, but insulating might help as well.

I just looked up your temps, and Vancouver is a lot milder in winter than I had imagined. Still, being outdoors, insulating might be helpful in temp regulation. Especially on keeping heat in if you are heating the water. Check out my IBC thread for pics of how I went about insulating an IBC. Lots of people insulate in different ways. There's a lot of examples on the forum.

I found a site a few years ago that explores extreme insulation in aquaponics, it might give you a few ideas. I think the guy is a member here as well. He uses old non working chest freezers with a liner as a fish tank. The freezer is already insulated. I thought it was pretty cool. I believe it's called Frosty Fish aquaponics.