Backyard Aquaponics
A place to discuss aquaponics

Hey all,

I'm confused and wondering where my issue is here. This is the third round of tilapia fingerlings I've put into my single FT IBC aquaponics system. They keep dying!

The most recent round was put in about a week ago, and after losing a few the last couple of mornings, I came home to find most of them dead on the bottom

I tested the water before putting them in. Here's the readings

Ammonia: .25
PH 7.2 (re-tested this after 4 days and found it to be 6.4)

Additionally, it's now been 11 weeks since I first introduced ammonia and started cycling the system, and I still have no nitrates!

Food is building up on the bottom because the fish don't seem to be interested in eating it.

One question I have is if fluoride in the water causes issues?

Help!

First. Don't leave uneaten food on the bottom. Scoop it out. Do you know your nitrite readings? Have you added salt to the system? If not, it might be wise to.
Resist the urge to feed your tilapia right when you get them, they are usually stressed when put in a new system, and they don't need the added stress from the ammonia they will produce once they do eat. Tilapia can go quite some time without feed. The tilapia in my indoor system has gone for weeks without feed.

How many are you adding? Don't believe the 100 fish in 1000 liters hype. With just the top of the IBC as a grow bed, I would probably only stock 20 or so tilapia. I certainly would be even more conservative with other fish.

Thanks for the quick response.

My nitrites are also zero, I've been checking them every time I test for the nitrates, ammonia, and PH

I suctioned the bottom this morning, and added salt, thanks for the tips.

Thanks for the tip on feed. I'll refrain from adding food for awhile.

The first round, I stocked 40, the second, 100, and this round, 50. Maybe that's my issue. My problem is, I can't find anyone willing to sell me small numbers. The second round, I got the 100 because the guys refused to sell me less than that, and this time, I was able to get him to agree to 50. I've called other fisheries, and most of them require a minimum of 200 per order...

Does the grow bed need to be stocked full while I'm cycling with fish? I currently have it stocked about 1/4 of the way full, because I've been waiting for the nitrates to show up.

I'm also confused about algae. It's an outdoor system, getting sunlight about 6 hours per day. If I leave it uncovered, algae starts growing. Some of the research I've done indicates that having algae is no problem with tilapia, others say you want to get rid of algae as soon as possible.

Thanks for any help I can get on here.

Load up on vegetables now. The worst that can happen is that some of them die off, but if you are planting from seed, it is pretty cheap. Some vegetables can even utilize ammonia. Lettuce I hear likes it. Algae can be a contentious topic. Tilapia do feed on it, so they prevent too much growth. The down side is that algae depletes oxygen at night, and can contribute to ph swings. The other down side is that you have less control on feed while you are cycling. Ammonia production increases with feed. The algae can act as feed. That being said, I don't have my fish tank covered. But then I am not dealing with fish deaths. Perhaps cover your fish tank while cycling, then once you are certain that you are cycled, remove the cover to get the algae to feed the tilapia.

Thanks again for the advice. I'll keep it covered then. For now, the deaths have dropped off. I haven't had any more dead the last two days.

Great you mentioned the lettuce. I was just transplanting seedlings from my nursery to my garden yesterday and had way more seedlings than I had space for, so I put a few lettuce in to see how it would go. I still have some left, so I'll go ahead and fill out the GB with the remaining lettuce seedlings from the nursery.

Thanks!

Hi, I am a newbie also raising talapia I just wanted to add that you stated you don't see any nitrates. Try looking down the vial into the test water, I noticed that on low reading you will see the color change when you look into the vial. My system eats up the nitrates quickly. Until I got it going for awhile I couldn't see the nitrates unless I looked into the vial from the side view it did't look like I had a reading, they where there just in lower quantities then the test shows from the side view.

The nitrate test is the most complicated of the API tests. I am pretty sure you have to hop on one foot while turning to the left and sing the "if I was a rich man" song from fiddler on the roof.

Hey guys, thanks for all the info. Lettuce is doing okay, and the fish are happy and content, all 15 of them. I tested again yesterday, PH is 7.4 and ammonia is .25, but nitrates still not there. I'll try looking down the vial. But I'm still seeing that the lettuce in my garden is growing faster and better than my aquaponics.

Should I try to look for a way to introduce the bacteria into my system? I started mid-January, so we're at three months now.

The bacteria is there, it just needs to grow.

What's the water temp now? You need to check for ammonia toxicity using the table on this page -

http://ibcofaquaponics.com/information/tables-and-charts/

I agree with Ron, be patient, you may actually have cycled but can't be sure at this point. Since you had lots of food at the bottom and the ammonia readings weren't super high it makes me think either your system cycled or if you have algae and it's taking in the ammonia and nitrites and using them for growth before the bacteria can break it down to nitrates.

If your system is cycled, the plants and algae could be using up the Nitrates fast enough that your kit can't detect them. Happens with mine all the time.