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Tilapia intermittently dying, thoughts on cause?
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Author:  wookinpanub [ Nov 17th, '15, 07:03 ]
Post subject:  Tilapia intermittently dying, thoughts on cause?
Issue:
Intermittent death of tocky mtn white tilapia, avg one every 3 days or so. Size has varied, most recently it is the medium sized ones dying off

System:
- 3 IBC Totes: All connected in serial to one pump tied to a index valve. All three FT's are plumbed to drain back to all 3 beds (so water is shared)
- Expanded Shale media
- Each FT is 150 gallons H20
- Initially added 15 fish per FT (1-3" in size) for total of 45 fish

Background:
- Initially added fish on 10/16/15, discovered that tanks were not fully cycled
- High nitrite levels for a couple weeks, salt added and water changed as instructed
- Was able to get fully cycled on 10/24 with nitrite levels getting into correct range

What has been happening since fully cycled until now:
- Water temp steady at 70-72F
- PH around 7.8 (buffered from expanded shale)
- Ammonia @ .25
- Nitrites @ 0
- Nitrates @ 80-100+
- No fish gulping at the surface (O2 levels would appear to be fine)
- GB are fully growing plants with solid growth rates, nothing being added to the plants (chemicals)
- I've been careful with feeding, once a day and what they consume in 5 min
- Fish are actively eating across all 3 tanks, and will dart around from time to time (not sluggish)
- I cannot find any signs of fungus or bacteria on dead fish (see pics), they look healthy to me
- Dead fish are removed the day found (I check daily)
- Water clarity is excellent

What I did today:
- Cleaned the bottom of FTs to ensure visibility / remove anything on the 'floor' that may be causing the issue
- I used a gutter guard (this: http://www.homedepot.com/p/Amerimax-Home-Products-3-in-Galvanized-Steel-Wire-Leaf-Strainer-29059/202091116 on the outlet inside the tank to prevent the fish from getting to the pump. It said galvanized steel, but it seemed almost a bit rusty when I cleaned them today.

Questions:
- Could it be the gutter guards I'm using? And if so what's a good alternative to allow water to flow but prevent the fish in that IBC outlet port?
- Something else and if so what?

Thanks!

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Author:  BuiDoi [ Nov 17th, '15, 13:56 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
Quote:
http://www.homedepot.com/p/Amerimax-Home-Products-3-in-Galvanized-Steel-Wire-Leaf-Strainer-29059/202091116


Alarm Will Robinson - Alarm, Alarm

GALVANISED :upset: = Zinc

Plastic Gutter guard will be the answer.. it should be even more common..

I am unsure as to how the three tanks works.. is it a case of water returns to the first tank and pumps from the third.... I do wonder how it will all go with moving solids..

I have (in another life) used security door mesh.. you know those security doors that have HEAVY black wire - it's painted stainless steel.. but it wont pass many solids..

And just a heads up.. Zinc seems to be VERY, VERY insidious, and "Gets Into" media and does not want to come out..
ie.. you can do a reading now and the Zn might be 10 (just a figure), so you replace ALL the water and a few days dater it reads 12 :oops:

Feel happy that you are not alone.. MANY on here have dried over lost fish from Zn..
even the best can get caught, and it seems to be that you THINK you are getting away with it and then WHAM.. it catches up - TOO LATE

SEACHEM manufacture a RESIN based filter material, that whilst expensive, is re-activatable..
I am looking to buy some to rehabilitate a system that I destroyed, thinking that I knew better..
I thought that rain flushing of galvanised roof, would not be in contact for long enuf to be harmefull.. :support:
..
.
Author:  wookinpanub [ Nov 17th, '15, 15:25 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
BuiDoi wrote:
Quote:
http://www.homedepot.com/p/Amerimax-Home-Products-3-in-Galvanized-Steel-Wire-Leaf-Strainer-29059/202091116


Alarm Will Robinson - Alarm, Alarm

GALVANISED :upset: = Zinc

Plastic Gutter guard will be the answer.. it should be even more common..

.


Ugh.... so much for that assumption of mine...

I'll look for the plastic version. I also see there is an aluminum version of the exact same downspout guard I might be able to get my hands on. Will using an aluminum mesh cause any issues??
Author:  BuiDoi [ Nov 17th, '15, 16:06 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
Aluminium also bad (as I understand) but not as bad
Author:  wookinpanub [ Nov 18th, '15, 03:52 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
I still can't believe that the rain padding over a galvanized roof created enough exposure to cause that much damage. :( sorry to hear that....

I found the plastic versions, thanks for the tip, they are now in.

Based on what you said about zinc staying in the system, is there a way of testing that without buying a special kit?
Author:  scotty435 [ Nov 18th, '15, 05:53 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
Send a sample to a lab.
Author:  superdave50 [ Nov 18th, '15, 13:30 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
+1 for the suspicion of zinc. Specially with the rust showing, that would mean that enough of the zinc has been removed to allow the steel to oxidize. Sorry for your losses!
Author:  wookinpanub [ Dec 9th, '15, 09:29 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
Opening this back up, as I'm continuing to get die off, plus the most recent 2 that died today had a characteristic I had not seen before (see attached pics).

For background, see the first post on history. From that point, the following has changed:
- Water temp cooling down to 68-70
- Still losing a fish on average of one every 3 days
- Had replaced the galvanized guards with plastic per postings above, potential of zinc in system but don't know amounts, etc
- Have not done any significant water flushing / filling as yet since initial post (only a 50 gallon top off)
- Have not cleaned the bottom of the tanks since the first post (about 3 weeks ago), some sediment on bottom of tanks but not excessive IMO

These two fish differed from other deaths in that there appeared to be a greenish color around the gills. Had not seen this prior, most recent death before was a week ago and I didn't see this characteristic.

In total I'm down to 35 fish from the original 45-50. I'd like to get this sorted, I don't really have the financial means to continue to 'tweak' / add to the system (or patience...). Getting more fish is a 3 hour round trip and I don't have the confidence that they would survive in the system as it is.

I'd really rather not end up going the route of swapping these tanks out for a lower maintenance raised bed of larger size alternative, but at least that is a lower cost / simpler maintenance option.

Thoughts are appreciated, thanks for the attentions.

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Author:  BuiDoi [ Dec 9th, '15, 12:03 ]
Post subject:  Re: Tilapia intermittently dying, thoughts on cause?
wookinpanub wrote:
I still can't believe that the rain padding over a galvanized roof created enough exposure to cause that much damage.


The problem with Zinc, seems to be that a standard "Test Kit" has initial detection levels, that may be above the lethal level for some fish, and so even getting a zero-level, may to inconclusive..

Again - the issue will likely be that the media may have stored the metal and even changing water, might not fix the issue..

Your comment about rain water flowing over the roof and not getting contaminated, is 100% what I thought.. but then... I climbed up there last week and was horrified at the rust appearing ALL over the roof.. Last time I looked it was fairly OK, but now - rust everywhere... :dontknow:
So much for thinking the Zinc would not come off that easily :upset:

I don't know what to tell you as I am still paddling that boat.. and I'm nervous about putting anything other than KOI in the death-system..

I think that were I starting again, then I would build the same thing as a hydro-ponic system..
ie.. SumpTank, plus GrowBeds, and work on mineralising Worm-Castings etc to provide most of the nutrients.. At least you are not then paranoid about what might kill the fish, and regular fish food does make the Aqua-Culture side, possibly not as attractive as one hopes..
...
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