Backyard Aquaponics
A place to discuss aquaponics

I have had 4 goldfish and 3 yabbies in my tank to get the system started.
After about a month I introduced 9 Silver Perch.

I was supposed to get 10, but one was dead when I arrived at the fish store.
They were sent overnight from Melbourne to Adelaide and one was dead in the tank.

About 1 day after putting the Silver Perch in, 1 died.
Today, 6 days later, I found two more dead fish. 1 goldfish, 1 silver perch.

I did a water check

GH - 120
KH - 0
PH - 6.5
NO2 - 0
NO3 - 0

I have only ever done a water test once before, and if I am reading it correct I believe these values are fine.

I notice they look partly eaten, chunks taken out, fins missing and such.

Could it be that the fish introduced some sort of disease, or stressed, or are the yabbies attacking them?

all of the above.

If you didn't quarantine the SP or at least salt bath then you introduce issues to your existing system.
You add stressed fish to your system so any issues in there already will flare up.

The SP would be stressed which is a bonus for parasites and fish issues.

the yabbies will take a chunk out of dead fish. Quite happily eat them completely if they are there long enough.
in cases fish will nibble on dead fish as well - but first vote goes to the yabbies.

less likely yabbies are attacking them live but it does happen if the fish stay still long enough or sleep near bottom.
sick fish near bottom would be vulnerable to larger yabbies.

finally did you gradually introduce the SP to your system water or just put them straight in ?

SP are not goldfish - they require more looking after, including salting of system.
They will die a lot easier as well.

system pars look fine. Bit acidic but fish shouldn't mind that provided they were introduced to the water gradually.
in an ideal world they like pH a bit higher.

Thanks for your reply.

I put the bag in the water to let the temperature equalize but then tipped them in. Is there a better way of doing it?

I didn't do any salting, I don't know what that is. I will google that now.



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You may have already found this nice article in the Lily & Fin magazine:

Lily & Fin Sept-Oct 2016: "Salt - Chicken Soup for Our Fish" by Myron J. Kebus, M.S., D.V.M.

It explains using salt for fish health pretty nicely and has some easy to use formulas:


Keep in mind the units of measurement when folks talk about salting a fish tank. It is common to discuss salt level in "ppt" (parts per thousand) rather than concentration as used in this article. In aquaponics, plants can be a salt consideration as well. Some plants do not tolerate salt very well (e.g. strawberries.) The same goes for different types of fish -- some tolerate higher levels of salt that might be toxic to others. Know your fish. Besides changing out water, it can be difficult to get rid of much salt. If doing a long term salting, keep track of how much salt you've got in your water as best you can. Assume the salt is equally distributed throughout the water. If you replace half your water with non-salted water, then your salt level will be cut in half. Replenish to compensate if you are trying to maintain a certain level.

--
Sam

>> I put the bag in the water to let the temperature equalize but then tipped them in.
>>Is there a better way of doing it?

that approach should not be used for any fish - including goldfish,
and particular not fish that require care after long periods of stress (eg. transportation).

even with goldfish and aquarium fish you also need to gradually introduce fish tank water in with the transport water over a period of time. The greater the difference between the water the longer the process requires as it needs to be done in small steps.

Many food type fish are sensitive to pH differences - and even small differences can cause a 'shock'
Fish that are stressed are affected worse. In an advanced system this can result in a whole crop of fish being wiped out and take some time to recover from. see below.

>>I didn't do any salting, I don't know what that is. I will google that now.

it is mentioned a lot in the forum - use the search here.

basically new fish should never be added directly to an AP system.
Fish from hatchery's and multiple storage etc can be carrying diseases or parasites.

the recommended procedure is to go through a quarantine and water transition phase.
have a separate tub or tank of sufficient volume for fish to survive for a week or so.
that water needs to be prepared to be as close to pH of the *original* system/transport water of the fish.
This water should be salted to 2-3ppt (2-3kg per 1000L, 1-1.5kg per 500L etc) and have air.
The new fish should be gently added to this tank (quarantine tank) and left to recover from transport stress for at least 48 hours - keeping an eye out for any signs of sick fish or things such as ich.

at this time if you have a system with different water parameters you slowly start removing quarantine tank water and replacing it with fish tank water at 5-10% volume until such time as the fish are basically swimming in system water. This step is particularly important if you run high or low pH or have higher levels of any minerals/nutrients etc in your system.

for food fish you should keep you system salted to around 1ppt.

obviously this process is not required for things like goldfish, but are procedures common to aquaculture fish raising.

The quarantine tank can also act as a hospital tank if you later have a sick fish.
It can be moved there and treated with higher salt levels than those in the main system.

Thanks for the feedback everyone.

I have always used that method of letting temperature match, then pour in for my indoor tank with no problems. That's what I was told years ago when I got my first fish. But I will do it different now.

As for my aquaponics fish, another one died today. I have since done a salt dip using a small amount of water from the aquaponics tank. Then added salt to the main tank before reintroducing the fish.

I used this page for calculating how much. https://www.hamzasreef.com/Contents/Cal ... ulator.php
Let's see how they go now.

>> I have always used that method of letting temperature match

thought I edited to add that this is also important, but edit didn't seem to register.
(I copied to the Quarantine thread so must have edited that one.)

so keep an eye when moving fish that the temps are similar as well as the water parameters.

what you did with the salting sounds fine.

hopefully things settle down.

1 week after salting the fish, no deaths.
Thanks for the tip!

I thought it was all good now, but after numerous more deaths, I only have 1 fish and 2 yabbies left.
Each time I would find half a fish floating in the top of the tank.

No idea what happened to one yabbie. But from 13 fish to 1 is terrible.
I have had fish indoors and a fish pond for years, never with this problem.

The water check shows similar levels to before.

As in my OP the goldfish were in the tank for around a month with no issues. They only started to die after the silver perch were introduced. The yabbies were in there before the silver perch also.

Could they have introduced something to the tank?
Where should I go from here? Drain and start again?

Darren has gone through most of the major things.

Sometimes nitrite spikes can cause deaths days (or a week) later. It's damage to the gills that takes a while to get the fish (salting the tank before they go in gives better gill protection to the fish).

Do you have any photos? If you're not too far from me, I could have a look and tell you if I spot anything wrong.

When adding new fish, without opening the bag, sit it in the tank for an hour, let the temp normalize, then scoop them out of the bag they came in by hand (or pour the water/fish into a net). The ammonia/nitrites in the bag skyrockets when opened, something to do with oxygen/nitrogen getting into the bag. But they need to be taken out of the bag asap once opened, or you could have problems.

This is a photo from when it was initially setup.



The water quality at this stage was poor due to the growing medium. I used the egg white method to clear it up along with filter wool.
Plants were added to the grow medium not long after.
The silver perch were not in the tank at this stage.

This is also only a temporary tank. I am trying to figure out how to get a 1000L IBC to my house.

Hi John,

Is that the fish tank at bottom (ie. 150-200Litres or so ?).
If so your system is overstocked and there is insufficient room for the fish and yabbies to coexist.


you may have been OK with 4 goldfish and couple yabbies but no way for 9 SP as well.
But suspect yabbie would have eaten the goldfish anyway (if they didn't walk away) as there is no where for the fish to go to stay away from them.

are you running that as flood and drain ? Poor fish would be pretty stressed.

I figured it was too small, but it's only temporary until I get the 1000L IBC, also they are only tiny fingerlings about the size of my thumb.



Yeah, flood and drain.
I have put some rocks, and bits of things in there to settle the water and create places to hide.

I guess it's just too small and I should wait until I get the bigger tank for the fish.

Hiya John,
Looking at your set up I'd say 40 litres of media which equates to about 2 fully grown fish...
No don't stop now, your system is a good starter and when you get your ibc you have a head start. You will need more grow beds though if you want more fish, remember 20 litres of media per fish.
So grab a couple more goldies, keep your water at 1-2 ppt salt and plant some plants to get a good batch of bacteria for when you expand.

Is the liters of media the surface area or the total volume? The total volume is around 90 liters, but I assume its more about the available planting area rather than the depth?