Backyard Aquaponics
A place to discuss aquaponics

My males have an obvious "pointy" but the fish are getting close to a kilo.

I read that females can be very territorial after they have their fry. I guess that's true. I took the two females out of their respective aquaria once they spit their fry -- and put them in a 200 gallon tank together. I found one floating a few days ago -- with all her fins ripped off. Two large goldfish died a similar death previously.

So I took the remaining female and put her in with the few babies that were surviving (maybe 10?) No more babies.

Fortunately, the other tank still has at least 100 fry that are growing at twice the rate of the others. Possibly their success is due to the automatic feeder I put on their tank. If it is genetic, I'm sad because their mother is no more.

I bought an autofeeder for the other tank but no more babies.... So we'll give her another chance to make a batch.

I'm down to my last two females. I need more tanks. And more time....

Ems, if need, you can still breed back siblings. You're trying to stock tanks, not develop a breeding line. The inbreeding could cause some deformities or higher mortality rate, but probably not too bad with just the one generation.

My male fish is busy digging a pit in the gravel and swimming back and fourth. He does not seem to be eating much (He's kinda a runt). Is that normal behavior?

Sounds like typical male tilapia behavior to me. Must dig spawning pit. Impress da girls. Do him a favor and put a nice piece of slate in the bottom of the hole if you have a undergravel filter. Give him a love shack, too.

For breeding would it be best to have gravel, sand, or nothing in the bottom of the breeders tank?

Concerning the genetic inbreeding, there are two issues, a positive and a negative one.
+ the fingerlings will have a better growth rate each time you inbreed to the best growing fish you have, specially if they are from the same parents and the same spawn
- the more you inbreed the more difformities will appear and the less fingerlings you'll be having

Do the inbreeding with two or three genetic strains selected for each of the caracteristics you want in the later brood stock you aim at: best growth, less male agressivity and the more fry by batch. The only problem I have found in doing this is that they don't want to breed if they are to similar so try to take the most different phenotype (physical aspect for those who don't know) fish in the same genetic line, it usually helps a lot for the breeding.

The second point is to feed the fry all day long, it is the most important for fry nursery. There's a few techniques for that, feeder with a big spyral type spring that gradually winds back up pulling a carpet covered with food. A feeder made of a pipe glued on a mechanic timer with a fine groove that lets a tiny bit of food fall along the day and mainly when the timer mooves.
If you feed at two or three times per day they will eat lots and it will fill there guts andd won't have a very good efficiency. If the guts are full they will consume lots of energy to digest a big mass and the energy balance between what they use and what they take will be lowered. And the body acts to it as an aggression and tries to get the food out as fast as possible, because of the energy consumption.
Example: christmas meal has tendancy to make us sleep because of the same principle. We wouldn't sleep if we eat the samee meal in three or four different meals.
I hope that you'll find this interesting

Very interesting, Amacafish. If you have a picture of a continuous feeder, I'd be interested. It does seem like my tilapia fry are always hungry. I have an automatic feeder that feeds twice per day but I hand fed them 4 or 5 times today and they are always hungry for more.

I was wondering if a demand feeder would be practical for fry.

This is the continuous 12 hour feeders we have at work to feed or fingerlings (not tilapia but sea bass).
I don't think that a demand feeder is easy to make for fry, they usually work with the fish touching a ball at the end of a pendulum.
The more the fish are frenzy for food the more activity under the pendulum the more it distributes.
For fry I had thought of a gelatin mix hardened on a rock that you put in your fish tank and have the fry pecking on it, they do this for marine fish and it works.
I haven't done a fish feeder with a timer yet as I was reproducing my fish when my wife was unemployed (best continuous feeder ever!) but I was thinking that a tube glued on the round moving part of an electric mechanical timer could do the job. The tube could be full of food and closed on the other end, hte side of it could be drilled with some fine holes or a fine groove and this would leak the food out of it at each move on the timer; Haven't done it yet maybe one day. If you try post it here please.
KudaPucat has thought of a system in his system thread too.

And Fry will eat all day if they can, have you tried growing cyclops or daphnia that could live in the fish tank untill they get eaten. I've that before and it works well. Or they sell some artemia permanent hatchers hanged inside the tank, haven't tried them but they look like they work well and let a continous flow or newly hatched brine shrimp out of it.

Here is a link in Canada:
http://www.aquanourriplus.com/boutique/ ... anguage=en

Forgot to attach picture, sorry, mixed between preview and submit

a hundred years ago I worked for a very short time on a barra farm. The feeders for the fingerlings were very small motors with a drill bit in the end. The motor turned the bit and food came out of the hopper (pretty poor description I know )

Thanks Jaymie, plus I got two more fishtanks today so more work for feeding might try to do global feeding for all of them with an air extractor to push to food in tubes.
cheers

How long are Tilapia eggs good? Would it be possible to ship eggs across the country and then have the receive incubate them to life?

DDMan, the questions has been discussed on the thread here
http://www.backyardaquaponics.com/forum ... .php?t=935

Thanks! The search function does not like me