View Full Version : All male / Mostly Male Tilapia Hybrids

10-26-2010, 09:19 PM
Great and amazing information with reference notations. Perfect! Thank you, I will post this in the other topic. THANK YOU

10-28-2010, 07:54 PM
Mostly pie in the sky. Pure strains are almost impossible to get. Supermales are the only viable way to go any more.

01-04-2011, 11:51 AM
Have you done it?

Most of the people I've run into cite literature, but have not been successfull themselves. I've crossed horonorum/mossambicus and niloticus/mossambica. I get nice hybrids, but no significant male bias.

I find temperature is much more effective at changing the ratio.

01-04-2011, 06:51 PM
Hybridizing is not natural, in my opinion, regardless of the good/bad reasons. If the Creator had wanted hybrids, they would not have been separated by natural barriers - Mozambique and Africa (an Island - Mossambicus and the Lower Nile River) and the Upper Nile (a river in Africa - Nilotica) and the MidEast countries (Israel and Syria - Aurea) and Madagascar (an island - Hornorum). It seems that mankind just keeps messing around to make these hybrids - they don't occur naturally except when mankind messes around with nature. If mankind hadn't put the different species together, they wouldn't have hybridized ') Just my 2 centavos ......

01-04-2011, 09:38 PM
Lets not go religious on hybrids. If the Creator didn't want them, He (She?) would not have provided a way for them to get together by wearing down barriers over time, or allowing them to diverge to begin with. Hybrids are the bread and butter of agriculture. You'd starve without them. Check the label.

Feel free to believe what ever you want, but think it through. Hybrids occur naturally whenever ranges of similar species overlap. Man just takes advantage if he's smart. Where would we be without the mule?

01-05-2011, 05:52 AM
For Hybridization to be true commercial application it needs to provide consistent results and be maintainable. Keeping two species pure and separate at a single facility has proven nearly impossible. Getting pure horonorum now is just about impossible.

YY males (AKA super males) seems to be the way to go. These can be developed without chemicals or hormones by just about anyone, but it is time consuming without the ability to do genetic testing.

The process is simple. Raise a batch of fry at cold temperatures ~70F for the 1st 30 days. This will produce mostly females with about half being genetically male. Breed those back to normal males and 1/4 will be super males. Without genetic testing, these super males need to be ID'd via breeding and checking the sex of the offspring.

You can buy super males, but they are costly and all are hormonally produced.

08-21-2011, 10:40 AM
If you buy a supermale, you can breed it to normal females and raise these fry at 70F for 30 days. Any females that appear will be genetically male. Breed these back to the supermale and 50% of the offspring will be supermales. Raise these at 70F for 30 days and some of these will be genetically supermale, but female. Breeding these with the supermale will give supermale offspring.

This takes a long time and requires lots of tanks. The sex of young fish can be checked via a process called gonad squash, but this involves killing the fish, removing their gonads, and checking them under a microscope. This only determines if they are a physical female or a physical male.

It is a lot less trouble just to raise your fry at 96F for the 1st 30 days. This will give you about 95% males. There are a number of papers on this.