A Community and Forum For Aquaponic Gardeners
Fish Dying... HELP!!!
New to the forum so I think this would be the ideal spot to post this...
I am one of two teachers who is in charge of our school aquaponics. I set it up last year with supplies given to us by a teacher at another school. It is made from IBC containers (used for organic agave syrup so not bad stuff) and is a CHOP system. Last year we had it up and running with 25 fish for a few months until I was gone one day, the sump tank got low and the pump stopped moving water. Sad to say the next morning only 4 fish were still alive. So, the whole thing got emptied for the summer, fish moved to summer smaller tanks.
Anyway, we set it all back up in August. Cycled. Planted. Added the 4 survivors from last year. Got 24 more fish. Plants going. Things are great. Was given 25 more tilapia from an organic aquaponics system in Sept/October.
Then Christmas Break comes. I was sick and went in the day before or the day of Christmas Eve and found a dead fish floating. Pulled it out. Fed the voracious fish! The custodians had been feeding for us. Then went back two days after christmas. Pulled another dead fish out of the tank, well the skeleton of a fish floating on the surface. Fed the fish who acted starved. Went back the next day and there was yet another fish white and floating! That made me angry so I unplugged their heaters. I know that if they get colder they will slow their metabolisms and stop eating. I assumed they were attacking to eat. The heaters were set at 68 and they weren't getting fed daily.
Following Monday I went in and no dead fish. I plugged their heaters back in. The next day all was well and they ate no problem.
Wednesday I went in and there was a dead fish. This time it was on the bottom of the tank. I pulled it out and it still had some color to it. Tested the water and everything was ok except Nitrates. Our plants are having issues and so their aren't many in there and with almost 50 fish (more like 45) nitrates can be an problem. But all the other fish seem fine and I figured this was a weak one that was picked off by the others. I did some research and it said changing the water could help with nitrates.
Thursday morning I went in and there were 3 more dead fish on the bottom of the tank. These too still had color where as the ones over break were white (before unplugging the heaters) and floated. These sunk. So, I drained about 2/3 of the tank which is almost a full IBC container. I think we have about 250 gal in there? Refilled with nice cold hose water and the fish seemed dazed but just cold. Friday morning all was back to normal and they ate no problem. Friday afternoon there was another dead one on the bottom!!!
Today, Saturday there were three more dead ones on the bottom!!!! I took new readings and pH is at 7. ammonia is 0.25 ppm, nitrites are 0, nitrates are 0. Temp isn't cold but the heaters are still set at 68 and are on. Some fish ate.
What is killing our fish!? (sorry for the long story) I have pics of the skeleton and of two of the three I pulled out today. They still have color.
Replies to This Discussion
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Permalink Reply by Patricia Brandenburger on
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They now have a massive air bubbler that runs and the pump to supply air.
I did not de-chloranate but never had. I normally don't switch out that much water. Even so, they were dropping before I changed the water. I guess it could have been from the nitrates before and chlorine now? We have city water at the school and it isn't very chlorinated to start.
Randall Wimbish said:Do you have additional air supply? Did you de chlorinate the water that you used for the water change or is it well water?
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I will test the hose water and as far as feeding I know I was the only one in the building between Christmas Eve and New Years so nobody else could be feeding them then. Now, there is only one group allowed to feed them and they know to check the feeding calendar and sign off on it when they have been fed. If someone else has already fed them, they don't. I will check in on that though.
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This past week I have been leaving my classroom computer on and it hasn't shut off. They were installing new Exit lights over break but the power wouldn't have been off for long periods and this week we still have fish dying and no new power changes. The air bubbler is plugged directly into the wall. The pump and heaters are plugged into a power strip. Only the lights are on a timer and they are plugged into a separate outlet. (our system is inside since it is Colorado and it gets cold out)
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I don't mean to play devils advocate, but I've tried thinking through all these things and maybe I'm missing something in my thoughts? I'd rather post my thinking and bounce ideas back an forth to find the issue. I'm dreading going into school today for fear of more dead fish. But at this point I'm feeling like I'm guaranteed to find at least one more. :(
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Permalink Reply by Scott Roberts on
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I'd recommend setting the heaters to at least 72 - maybe even 78.... tilapia prefer warm water, and when the water temperature is lower, not only is their metabolism slowed down, but their immune system is greatly compromised.
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I found 3 more today. :( One of them was a survivor from our de-gassing last year.
I will crank the heaters up tomorrow and see if it helps.
Also, I don't know if this would have anything to do with it but I pulled a small piece of chain out of the tank. It was in there last year since we added the bubbler. The hoses are wrapped through it and the chain weighs them down. I did notice that the chain was more rusted than I thought it would be. Would rust affect them?
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Permalink Reply by Vlad Jovanovic on
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The rust would not, but if it was a galvanized (zinc coated) steel chain (the types commonly sold at hardware stores)...that would certainly have the potential to affect them.
Zinc, along with copper are both highly toxic to fish. They are even more toxic when found together...much more than either alone would be (synergistic toxicity effect of Zn and Cu towards aquatic life has been well documented).
The Littleton CO water quality report for 2014 shows an allowable limit of 1.3ppm for copper...with one site testing above the allowable limit. Average for August looks like 0.64ppm Cu
The LC50 (lethal concentration it takes to kill 50% of the test population) for most fresh water fish is only 0.5ppm (and can be as low as 0.006ppm in some particularly sensitive species).
Again, your drinking water tested at 0.64ppm for copper. (and any zinc from the chain would just enhance the effects of toxicity)...
Also, as carbonate hardness in your water goes down...metals like copper become even more toxic (than in hard, high pH, high KH type waters).
There's my 2 cents
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Would the chain affect them after almost a year (minus the summer) of being in the tank with them? I turned the heaters up on Monday to 72.
It is out of there now anyway. And I haven't had time to look at the water report, but we are in Unincorporated Littleton so I don't know if that water report would cover us or not. We are like the step-child of Littleton; we have a Littleton address but no support, money, or even emergency services provided by Littleton.
Anyway. Monday was good, no more dead fish after 6 this weekend. (3 Saturday, 3 Sunday) Yesterday (tues) went in and picked another one up off the bottom.
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Another one found dead this morning.
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Metal toxicity (zinc, copper) doesn't kill fish immediately (unless levels are quite high). At low sub-lethal levels it chips away at internal organs and/or gills slowly crippling their ability to function until one day...Whammo! Your fish are sleeping with the fishes...
IME when this type of "mysterious" fish deaths occurs...and water quality parameters have been consistently good, and their are no outward signs of disease...the deaths invariably lead back to some forgotten about metal elements (copper and/or zinc)...Which doesn't necessarily mean (written in AP stone) that, that is what is killing your fish, but it's a really, really darn good candidate.
IDK about Littleton Un-incorporated, but Littleton's Cu average is already well above the LC50 for most fresh water fish...couple that with the chain (you never did say if it was galved or not) and it creates an avenue certainly worth pursuing to solve the 'mystery'...
(in truth, such a thing has happened to many a person before you)...
Patricia Brandenburger said:Would the chain affect them after almost a year (minus the summer) of being in the tank with them? I turned the heaters up on Monday to 72.
It is out of there now anyway. And I haven't had time to look at the water report, but we are in Unincorporated Littleton so I don't know if that water report would cover us or not. We are like the step-child of Littleton; we have a Littleton address but no support, money, or even emergency services provided by Littleton.
Anyway. Monday was good, no more dead fish after 6 this weekend. (3 Saturday, 3 Sunday) Yesterday (tues) went in and picked another one up off the bottom.
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