Backyard Aquaponics
A place to discuss aquaponics

Thanks, That would be so much easer than trying to figure out which is male of female. Just give them a press and see what comes out.

Not even giving them all a press, just check the ones with the mouth full.

Eggsize, if I need to find a screen to hold the eggs sizes in mm:

Fish Length Diamater Width
Tilapia mossambicus 3.0 2.1 2.4 2
Ophthalmotilapia ventralis "orange" 4.9 3.5 3.9 1

Its catching the little buggers that hard. Im am going to have to get them into a bigger tank. I need to separate out males from females so that they only breed the way I want them to.

I don't know for sure, i'd say 2mm in diameter.
Check the www.fishbase.org website.
I'd go for the tubes if i were you, easier to clean, simple to regulate the flow and a lots of small units for a permanent use since you won't be creating a specific spawning time.
The pic of the systeem seems quite easy to do with little equipement.
The incubators were to hold a few hundred eggs since they were determining the spawn by introducing the males with the females.
By the way your website is nice, nice pics. I'll have to ask you a few question on the horticultural techniques when i'll be starting my system.
Not now because it will a demonstration system in a growshop.

I found something interesting.



Perhaps it is not worth the effort to try for all male culture? But, every other commercial site says the fish grow better when they do not spend energy breeding... Hmmm.. Food for thought.

the eggs my tilapia had were a tad smaller than 2mm

Check this
Egg Morphology of Oreochromis niloticus niloticus

max Ref. min Ref. mod Ref.
Egg diameter (mm) 4.3 2.5 42048 3.6

Eggs are like hen's eggs, pear shaped and yellowish brown in color. The size of ripe eggs varies individually, without relation to the weight of the whole ovary. The major axis in eggs range from 1.2 to 1.5 times the length of the minor axis.

So this should answer your question.
From fish base

Goodness...I get busy for a day, and the tread takes off.

Yes, it was Bardpaper on eBay, but I think he sold everything he had.

From what I gather the following is the best fish for meet production and cooler climates:

The key for Tilapia in colder subtropical and temperate regions

The ND 41 is a hybrid Tilapia cross between:

· Female - O. aurea ND-4 Tilapia family line
· Male - O. aurea ND-1 Tilapia family line

The economic traits of the ND-41 Tilapia hybrids are:
All-Male population without hormonal treatment for sex reversal
The ND 41 Tilapia hybrid are all males. The proportion of Tilapia males in any spawning cycle is ~ 98%, without hormonal treatment, and provided APT operational instructions are adhered to. Actually, the progeny is 100% genetic males. The lower percent reflects penetration of foreign fish, assuming stern protection methods are used.
Docile behavior
ND 41 behaves less aggressively than Tilapia O. nilotica. This becomes evident during sampling, sorting, selective harvesting and final harvesting. Fish are calm, not jumping and cooperate in routine farm activities. This results in reduced losses of fish throughout the production cycle.
Fast growth
The growth rate of All Male population of ND-41 Tilapia hybrids is higher than O. nilotica Tilapia in the temperature range of 22-25 °C, and lower than O. nilotica in the temperature range of 29-31 °C.
High fecundity
The ND 41 Tilapia hybrid yields 300 fry per-female per-month, at initial phase of maturity, reaching ~500 fry per female per month at full maturity. For production of 1000 ton per year, it is recommended to use a flock of 1000 ND-4 females and 250 ND-1 males.
Spawning at low temperature
ND 4 and ND 1 will begin mating behavior at 18 °C. Mating and spawning is apparent in commercial flocks at 20 °C. Hence, the spawning cycle of the ND 41 cross is significantly longer than that of O. nilotica in temperate zone and sub-tropical climate zone, and even during the 2 months of reduced temperature in Tropical regions.
Sensitivity to Streptococcus infection
The ND 41 is as sensitive as O. nilotica.

Thats to bad! You know its not easy to source tilapia! I am keeping my fingers crossed that I have a male hornorum! I lost so many to the pump and I lost one that was most likely a male to getting tangled up in a net.

Everybody will tell you that their own lines are the best. ND-41 is specific to a particular company, isn't it? I'm doing fine with mixed-gender and some fish maturing faster than others. After all, I can't eat the whole tank-full at once.

I agree with you janet plus, the juvenile eat the frys so the population does not get too big, nature has a way of evening out stuff.

However I was thinking about a tank/system with piranha, so if there is overstocking of little fish i could feed them to the piranha and not lose out on any nutes.

CG: Better to go on hemichromis liffalili to keep the fry at low density. The Piranna will bite a piece in the adults without any problem and won't even try the juv if the pond is well stocked.
They are small african cichlids and could be used to prepare the fish food for the tilapia.
They are used in africa to stock the ponds with tilapia and catfish.
Hemichromis is for the fry and the catfish is for the juveniles, then no need to seperate the males and the females, the growth will be slower for the tilapia but the biomass in the pond will be better at the end because of the different feeding modes.
They are called red jewel in aquarium trade, they breed well and get to a size of 7 cm in 4-5 months, quite agressive with smaller fish but not to much with bigger ones.
Check them out on fish base and you'll see.

Thanks Amacafish i will read up on them right now.

I was thinking pirana in a separate tank conected to the same system, i just net out the juvs and put in the pirana tank that way i dicide which fish get eaten. Once they are over 2inches i would be able to see if they have the disired traits and if not.......... If i use preditor fish in the same tank as the talapia i have no control over wich/how much get eatten.

Tilapia are really good at reproducing, my system is now cycled and with the water clear i can see the amount of juvs, let me tell you, i got more fish than i can handle, i estimate 800+ and that's after only 4 weeks.




here a pic of a random shot of the pond.