Backyard Aquaponics
A place to discuss aquaponics

It's been quite a while since I have been on this forum. My IBC system has been going great for a few years now although the Silver Perch have been the slowest growing fish ever!!! I have had them in there for about 2.5 years and they were finally getting close to plate size (small plate anyway) and then in the space of 24 hours I came home tonight to find them all dead and at the bottom of the tank!!

Not really sure what has happened. I checked the levels (something I haven't done for over 12 months) and the Ph was 7.4, the Ammonia between 0 and 0.25, the Nitrites 0, and the Nitrates 80 which is pretty much exactly the same as the last time that I checked it.

On the weekend I did cycle the two constant flood beds (I do this ever month or so) which makes the water pretty cloudy for a couple of days but things had cleared up by last night. I also topped up the tank with about 50 litres or so of tap water (same as I have done lots of times before) and so there has really been nothing outside of the ordinary as far as I am concerned.

I fished out the 11 dead fish (I started with 24 fish 2.5 years ago and lost a few early but these 11 have been the survivors for the past 18 months at least) and took a couple of photos. There seems to be some weird black patches on some of the fish and some red on their "cheeks" that I hadn't noticed before although to be fair they always hide up the back of the tank and are quite hard to inspect in detail.

Anybody got any ideas on what might have happened? I initially thought maybe a big spike of Ammonia but that doesn't seem to be the case??

Gags

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How well do o recognise those images..
Exactly like my SP.. those bleached patches, those gaping mouths..
We (royal.we) have come.to agree that mine died from Zinc, because I sametimes used water collected from a gal-roof..
Other reports of zinc poisoning seems.to agree that t builds up in the system.and reaches a.trigger level..

The first deaths were blamed on electrocution from a leaky system pump

The problem.is that you are suggesting.no zinc water ...

So problem.. yours look like mine and I first blamed.electricity... is there any chance.you have a faulty pump

Q... to a fish expert.. what is that bleached patch caused by

..
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I'd be tempted to say it's a bacterial thing. With the discolouring on them.

When you say you cycle the constant flood bed every month, what do you mean by that?

But the flared gills & open mouth usually point to a poisoning of some kind, chlorine/zinc/other chemicals.

There hasn't been any round up or something used around the system?

When I say I "cycle" the constant flood beds I put in a bell syphon for a couple of hours so that they cycle through flood and drain - the water always goes a bit murky after I do this but two days later it is crystal clear again and then I use a short bit of hose to syphon out some of the solids off the bottom of the tank.

A couple of guys feel that the mouth and gill thing is an unreliable.tell-tale, as it can.also be a natural muscle response.

I have not made up my mind, and the interesting thing of how some are normal looking, and yet they surely died from the same problem..

I again, am supercurious, as to if there of an electricity problem..
..

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And for what it's worth...
I asked a SP breeder about my deaths.. he commented that death from an event would typically take four days..
And that once "injured" by an event, they could look pretty normal until death..

Again, I am so interested.in that bleaching just like mine..
I am pretty sure that the breeder did say that could accompany electrocution, and when I say electrocution, I am talking an electric field.. a voltage gradient..
During the night that mine died I saw them swimming at the surface, breaking the water, but not gasping for air. They actually looked they were trying to move away from "something"..
I noticed the electrical tingle when retrieving bodies.
The real smoke screen started when the pump had been replaced and new fish died after four days..
I "speculate ", that the Zinc was also there and whilst tolerated by the dead ones, it was a lethal slug to new ones..

Did you.salt the water.. light salting ( 1kG per 1000L) can sure help with nitrites susceptibility ..

But given.that few have come.forward with opinions, (and i understand why) , I would throw in the possibility, that the FLUSH may have also flushed an anoxic zone and the nasties took that four'ish days to complete their dastardly works...

I have developed the belief that solids removal of a good thing.. (with off-line processing) and I wonder if that would help with you solids being flushed from the GB.. I know this is completely ANTI-BYAP ... but I am encountering more and more who see solids removal as a.good thing..

FWIW..... I have near 150 fish in my new 1PPT salted system... I remove ALL.solids at least every two days .. no real grow beds.. but Bio filtration .. pH is 6.2, Ammonia showing API - 2, Nitrites - 0.5 and nitrates currently zero...
All seem to be pretty happy.. And growing well.

Ain't it hard to work out the real facts...
.. Peter