Backyard Aquaponics
A place to discuss aquaponics

I was feeling sorry for the male breeder stuck in his floating cage in the main grow-out tank, so I put in double dividers in one of the aquariums and put him in there. I put the male on the left, 4 inches (100mm) of No Man's Land, and then the females on the right. Today I learned that this arrangement will not prevent tilapia from breeding. I'm hoping that most of the eggs are not fertile, but I won't be that lucky. So now the male is in with the fry/fingerlings. There's a divider in that tank and the fry can swim through it (this week) to take refuge from the male. I'm hoping he thins the ranks a bit, though.

Lately, I've just resigned myself to leaving the broodstock together and letting them do thier thing. Every now and then I see fry or a fingerling or two, then woop...they vanish.

How many fish do you reckon you are up to?

Those fry look like they're growing quickly JP...

Hi Mike, I have about 55-60 of the original fish, and well over 100 small fingerlings from the first 2 spawnings. I'm thinking that if the male won't cull the fingerlings, I will do it in the next week or so. I'll use the best for the next grow-out batch.

I left the males and females together in the main tank. I can hear them chasing about in there sometimes (big splashes and bumps), but there are enough other fish to get in the way that any violence is shared and dispersed. Fry apparently vanish immediately upon release since I have never seen one in there.

My concern with the breeders is that I don't want them injuring each other. A female about to release her fry can get rather nasty. If there are only 2 other fish in the tank, she can focus a little too hard on a single fish. I am working with 50gal aquariums, but they are only 3 feet long. That apparently isn't quite enough space to let the other fish get far enough away from a brooding mother.

EB, they are growing like weeds! I have never seen fish grow so fast; it's rather frightening.

i like how u used the rope for supporting the tom i been toying with using chicken wire but can't seem to make it work and look clean maby ill use a big wooden dowell or somthin

I was wondering how to best breed Tilapia without having to spend too much time working with and/or worrying about them. If they are able to spawn across a 4" gap, then I think I may have an idea - tell me what you think-

In my proposed system's (design #5, build #2) header/fry/breeding tank I was thinking that with some mesh dividers (big enough mesh that fry can swim through when they are spit out), divide the tank into sections: Stud headquarters, multiple harem cubicals (2-4), then the nursery. One end of the tank is Stud City, the other end of the rectangular tank is kids land. In between you have the harem areas. Each fish's area is a small rectangle where they are the only ones. If a female is ready to spawn, since Janet found that a 4" barrier didn't stop them, direct contact through a mesh barrier shouldn't slow them down at all. The male would have a common mesh wall with the female.
Jump ahead a bit, and the female spits the fry and they move away from home (the nursery that also has a common mesh wall). Occaisionally, I could net some of the fry from the nursery tank and into the grow-out tank. The brooders could just keep on doin' their thing, and everything should be reasonably intervention-free.

Thoughts, Janet?

it is this reason why there are hefty fines for having them in Queensland
I like them, but the law does not

That sure is a determined fish!

Hi Greenedo,
You could definitely breed them like you propose. It would protect all fish from injury, and you would still get a pretty high fertility rate on the eggs. The only hazard I see is predation of the smallest fry by the larger fry, and some predation of the fry by the adults if the fry weren't fast enough getting to the Kids Land. Although the adults are fairly vegetarian, the fry/fingerlings can be rather carnivorous. Then again, with the prolific nature of these fish, losing some of the youngest fry probably wouldn't be a major problem. Maybe you could set up the water current to direct fry (and milt) from the Bachelor Pad to the Harem Tent to the Kids Land.

Good idea! I was thinking that I might have wanted to have the current the opposite direction to keep the fry from being sucked into the GBs, but as long as I have a screen on the intake, it shouldn't be a major problem, and as you said with the prolfic nature of these fish....

I figured that duckweed in the top of the tank would also keep the fish in salad and give the younger fry someplace to hide. I figured bird netting would make a good mesh for separation - easy passthrough for small fish, but no way that the bigguns could get through.

One more question - I have read that in mixed-sex growout tanks, having some kind of predator keeps the fish moving and keeps their mind off sex, thus allowing them to get bigger faster. What would be a good fish to keep them in line?

Hey Greedo:
Make sure the netting is strong - I found one of the big rocks holding the plant basket for a drain screen on the bottom of the tank yesterday. I wasn't the one who moved it!

I would look at a channel catfish if you want a predator in the grow-out tank. I don't have a predator, and frankly, they are growing very quickly anyway. No problems on that front. I could feed them twice the amount that I do (and they'd probably grow twice as fast) if my plants could handle that amount of nitrate. (C'mon tomato, climb that rope!)

Oh, my dividers are made out of a piece of diffuser for a fluorescent light fixture. Just the cheap 1/2 inch grid type. Nice and rigid, I just wedge it under the filter. I would be afraid that a tilapia woudl swim right through bird netting. They are strong fish, and mine are only 6 inches long. (150mm)

Or they may damage a fin if it gets caught in bird netting.

Good points, I will adjust my virtual system in preparation for a real one.

(I just need more time....and money....and good looks....and brains....)