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Tilapia Babies in Sump Tank

I am newbie to AP and I've only found one other person doing aquaponics in my area (Nashville.) So I'm just blindly plugging along. My system is about 7 months old, 300 gallon tank with 2 grow beds in a greenhouse. Doing great, have forty 6-8 inch tilapia, plus 5 little koi. Had veggies all winter :)

Also have about 30 T babies, all varying sizes in my 75 gallon sump tank, guess they escaped the big tank thru the pipes. Starting seeing them in Feb--I thought the water had to be at least 80 to breed???? Anyway, they seem to be very happy there and not causing any problems...except that I don't see any of the really tiny gray baby fry anymore.

I'm wondering if my 2" babies are eating the fry...so I thought I get get the big babies out and perhaps put them in a 60 gallon tank that I'm wanting to grow duckweed in. Is that possible? I know duckweed needs the fish poo but doesn't like water movement. I thought maybe a small aerator on one end would be enough for the babies and the duckweed would grow at the other end. (And add some mosquito eating fish too since that tank is outside). Pls LMK if that is feasible

And does anyone know what size fingerling are safe to put in with bigger fish? Can an 8" fish eat another fish that is 1-1/2"?

Thanks for any advice!!

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Replies to This Discussion

Permalink Reply by Dave & Yvonne Story on June 12, 2014 at 1:36pm

Sounds like you are doing a GREAT job. Yesterday, I gave a talk about my experience with tilapia in a sump. I put a nylon over the pump intake to keep the frys from being sucked in to the pump.

As far as the duckweed, again my experience is that tilapia love it. You will not have the desired growth rate in your tilapia if you keep them on a duckweed diet.

I heard a cute phrase about small tilapia being eaten (popcorn). Anyway, once a tilapia fry is a fingerling, they have learned to escape and evade.

Again, GREAT JOB

Permalink Reply by Connie H on June 12, 2014 at 2:16pm

Thanks so much! As you know, it's so fun :) Is the talk you gave on youtube?

So, it is safe to put my 1-1/2 fingerlings in with the big boys? I will begin to harvest the big ones in July or August and I would love to have the fingerlings to replace them.

I use organic fish feed and thought I would add the duckweed as a veggie for them. I also feed them worms and BSF larvae from my compost bins occasionally. I wish they would eat my tomato suckers but they don't seem to like those leaves as much as my mesculun lettuce leaves that have aphids on them, hah!

Do you think the 2" fingerlings can eat the fry? I don't see any at all :(

Permalink Reply by Julie Coates on June 12, 2014 at 4:34pm

Connie - I am glad you asked. Don't have the answer but I have a similar problem. I don't know if the smaller fish will eat live fry but I saw one of them eat a dead one today. I bought a one of those cheap plastic containers and threw a small filter on it and put the little ones in there. Hope someone answers that has some experience . . .

Permalink Reply by Dave & Yvonne Story on June 12, 2014 at 5:06pm

fun. To me, going to places no one has gone before is the best part of having fun. No body will do things exactly the way you do with the success you will find. As a fellow traveler, I am interested to hear about your successes and not so successful trials.

Permalink Reply by Bob Campbell on June 12, 2014 at 11:47pm

Yes the 1/2" fry will be eaten very quickly by 2" fingerlings. Tilapia are ravenous carnivores until they become full grown adults and then you still can't trust them.

Permalink Reply by Connie H on June 13, 2014 at 8:24am

Bob Campbell said:

Yes the 1/2" fry will be eaten very quickly by 2" fingerlings. Tilapia are ravenous carnivores until they become full grown adults and then you still can't trust them.

Thanks, Bob, for confirming my suspicions! Any advice on how to catch them? My sump tank is a large oval that is almost completely under my IBC grow bed. I have been using a liter plastic bottle with 1/3 of the top cut off and inverted in the bottle. Works pretty well, but slow, catch 3 or 4 a day.

Permalink Reply by Dave & Yvonne Story on June 13, 2014 at 4:05pm

My experience is NOT 1/2 inch being eaten by 2" inch tilapia. So, I took a spin over to a tilapia breeder here in town to see what his experience is. He showed me that he had 3/4" in with 2" and his belief is that if the fish are satisfied with the food available, they will not eat anything 1/2" or larger. I would add to that, some tilapia have a "mean streak," I mean they are bullies and will chase and stress anything smaller than themselves, sometimes resulting in the death of the smaller fish. When I was starting out, I kept 5 big fish tanks in the house to try and learn about these fish and breed them, If I saw a bully develop, I took him out to an aquaponic setup and released him into one of my large tanks with my full sized tilapia, It is all fun and learning. Relax and see what your experiences are.