View Full Version : Massive fish die off.

12-22-2013, 09:33 AM
Hello everyone. I have returned. Been very busy raising my baby boy, work, and keeping a garden over the last year. My ap system is over a year old now. We ate a tilapia about a month ago and I joke around and tell people that it was the best $1500 dollar fish I have ever eaten. Since I have around that much in the whole system and only have eaten one fish. Actually, we ate a second one when some of our out of town guest visited and again, it was the best fish I have ever tasted. I had eaten a few tilapia at different places and some I could tolerate and some were extremely grassy/fishy tasting... so I was pretty nervous about raising them in a closed system. I even read here on the forums that someone said that ap tilapia taste awful. I am very picky when it comes to eating fish and I found my ap tilapia to be wonderful. Actually, we cooked the whole fish, (my wife is Asian) and I found myself eating the skin, dark lateral meat, and even the fatty parts. Wonderful, absolutely downright tasty.

Now that I am hooked on the ap tilapia, I have a problem, there dieing!

Brief background info about my system (already posted detailed info before):
Fishtank: IBC tote about 250 gallons. It overflows straight to the grow beds (I realized later that I need a swirl filter first) Will add one later when I revamp my system.
Growbeds: 2 3x8x12 gravel flood and drain setup with bell siphons. (when I had only one gb, I had perfect operation of bell siphons. When I added the second gb, started having major issues with making/breaking siphons and such. I think I plumbed it with too large of pipe, or beds stop up too fast from not having a swirl filter. Growbeds then drain into a sumptank.
Sumptank: @ 3x6x3 This then is pumped into the fishtank starting the cycle over again.

I have (had) a male and female adult tilapia in the sumptank as breeders and lots of baby tilapia from 1" to 3" in size. Maybe 75 babies. Also there are about 20 - 30 large snails in the sumptank. I have (had) 9 adult tilapia in the fishtank with a few babies now and then. We ate two tilapia out of the fishtank recently so now there is only 7 adults and maybe two 3"-4" ones. Over the last year and a half, I haven't done much to the system other than feed the fish rolled oats, top off with water, and tend to the plants. It has been really a sweet setup and easy to maintain.

Now to the PROBLEM:
About 4 weeks ago, I accidentally left the water hose on while topping off the system. It probably overflowed the sumptank for a few hours. Maybe four. Well, a night or two later, I found my first dead baby 1" tilapia floating in the sump tank. First time in over a year and a half that a fish died. I did a water test and didn't see anything out of the normal. I just figured that maybe the temp had dropped a little low during the water change from all the fresh well water running in (we do have a sulfur aerator holding tank and a salt water softener for our house water, which is what I use to fill the system). Maybe even the oxygen got low too as the beds were not draining correctly, so I cleaned out half of the oldest bed and tweaked the drains to flood and drain more evenly. I replanted lots of different lettuce.

Our temps maybe dipped down in the low 60s a few nights later. Next morning, had another dead baby. Thought that it was just a fluke. Several days later, I find a few more babies floating. Starting to get suspicious, but contributed it to the cold night a while back. I did move the water heater to the sumptank, turned it on, and set it to 65. A few more nights, same thing... except it was a lot more dead babies. And I found two baby tilapia (that I didn't even know was in the fishtank) in the growbed drain area. Both were still very alive so I put them back in the sumptank. Now my work has gotten extremely busy, so I haven't done much to the system other than raising the temp to 70, and trying to keep up with cleaning out the dead babies. Sometimes it is five at a time, or up to 10. Just when I thought I have lost all the baby ones, I find a few more dead the next day. Once again, the water test seem normal.

Now to the devastating news:
I found my female breeding tilapia upside down this morning, freshly dead in the sumptank. I removed her and examined the gills, they look perfect. She has some color missing from her tail and a few scuff marks across some scales, but other than that, perfect. Eyes are very clear. In fact, I was tempted to put her in the oven. But, to the compost bin she went since I don't know why she died. I collected some water from the drain pipes of both beds and am posting the results here in hopes of maybe saving my other 8 adults.

It looks like the ph is 7.6, Ammonia 0, Nitrite 0, Nitrate 15

I will test the ph three times a day now, to see if I am getting huge swings.

Roger L.
12-22-2013, 12:06 PM
I'm fairly new at this, about 3/4 year, and like you it would seem to be a water issue being as the problem arose when the hose was left on. Do you have an aireation system in the tank? If not, that would be a cheap addition to the system to eliminate the lack of oxygen issue. Have you stopped feeding for a while? When fish are stressed that should be done as you attempt to solve the problem. They can go quite a while without food. I'm sure some of the more knowledgable people will chime in, but this is what I would do first.

12-22-2013, 06:09 PM
Thanks Roger L. for your response.

I have added 4 airlines to the system today. I had it laying around from the time I brought the fish home. I did another ph test and it was exactly the same at 7.6. I will test it again right before bedtime and just before sunup tomorrow.

I thought about the DO, but when the hose was filling the tank, it was just spraying a hard fine mist on top of the water, as I figure if I do it the way, it would add to the DO.

I have slowed down the feeding before the dieoffs, as the temps were getting cooler and the tilapia quit eating good. Now I only occasionally add some rolled oats, maybe every other day.

I used a flashlight tonight and I have 1 female breeder and one 3" baby left in the sumptank. The fishtank is too deep to see any babies, but the larger fish are still hanging in there.

David - WI
12-23-2013, 01:58 PM
Did you check your pH with the "low range" test?

It looks like you might be "off the scale" on the low end... possibly it's much lower than 7.6?

12-23-2013, 02:25 PM
Did you check your pH with the "low range" test?

It looks like you might be "off the scale" on the low end... possibly it's much lower than 7.6?
Yes. It was right at 7.6 as well.

I did do three different water quality test over last night and early this morning, two from the grow bed discharge and one from the fishtank discharge. All were the same although the fishtank discharge was a little lower in Nitrates, I would have thought it would be the other way around.

I had no more fish deaths so far... although I only have two left in the sump tank... Perhaps the aeration is helping... seems weird to go a year and a half without it just fine, but then need it all of a sudden.

01-27-2014, 09:36 PM
Hi, I know this is unrelated but I was wondering if someone can help me. I posted in this thread because it has the most recent post that involves tilapia.

I got 11 blue tilapia about 3 months ago and have kept them in a 100 gallon rubbermaid bin. My water quality isn't as clean as it could be but they seem very healthy. They are about about 10 inches long. I just saw tonight that one of my fish is light pink! I know blue tilapia can become pink in some spots, but it's whole body is pink. I've researched this and couldn't find any thing a blue tilapia becoming pink all over it's body.

I don't know what variety blue tilapia they are. As far as I know they are plain jane blue tilapia. I don't know if certain varieties change color as they age. So far there is only one that is pink, the rest are dark blue for the most part of their body. I inspected every one of them when I bought them. They all were dark blue and the same. If anyone can help me out with this it would be much appreciated. If someone is willing to help I will try to get a picture up of one of my normal looking ones; and a picture of the pink one.

01-27-2014, 10:57 PM
Ikemm7, You have a blue tilapia that turned pink...I have several of my pink tilapias that are turning med. to dark gray (maybe blue, I never seen what the blue tilapia look like).

Back to Lordshandyman, with the amount of water that got added to the system my guess would be you flushed out all of the oxygenated water. Your GB's help to stabilized your other readings but your system would require a longer run time to rebuild your oxygen levels.

Roger L.
01-28-2014, 08:07 AM
lkemm7, I also raise Blue Tilapia. Some of mine, mostly the males will turn pink sometimes. They seem to be more aggressive then and may have something to do with showing off for mating or territory protection. Then the stripes will reappear at times. They seem happy so I don't worry about them.

01-28-2014, 09:18 AM
With regards to the OP, I think there could have been 2 problems that your test kits don't test for. How is you water sanitised? If it uses Chlorine or Chloramine, I would guess there was a bit of poisoning to your fish - it's pretty harsh on young fish and can significantly hinder an adult fish's immune system.
The second problem I can see is the fact that you add salt to your water. While tilapia can tollerate significant ammounts of salt, a fast shift in salinity can cause osmotic shock (though, I'd expect to see that in the plants as well). Osmotic shock would affect young fish a lot more than adults, as well.

01-29-2014, 07:40 AM
Back to Lordshandyman, with the amount of water that got added to the system my guess would be you flushed out all of the oxygenated water. Your GB's help to stabilized your other readings but your system would require a longer run time to rebuild your oxygen levels.
I guess I would have to agree with you, but I would have thought the water would have been oxygenated by the desulfering process. For those that do not live in southern Florida let me explain, we have a @300 gallon water holding tank that we spray a mist straight from our well into, to release the sulfur. We then pump the water through a water softener into the house or my fishtank as it were