Original Male Tilapia (OMT)

This technology allows to produce all-male fry. TIL-GEN L.A. S.A in Costa Rica continues to develop this technology for distribution in the world.

YY Supermale Technology

It is a breeding program that combines feminization and the evaluation of offspring to produce new males with YY genotype (i.e., with 2 male chromosomes) instead of the usual male genotype: XY. These YY males, known as "supermales," have the extraordinary ability of producing offspring with sex rates that exceed 98% male. These offspring are called Genetically Male Tilapia = Original Male Tilapia (OMT). They are genetically normal males. TIL-GEN offers YY males, which are proven to produce between 98-100% true males.

It is TIL-GEN’s belief that economic characteristics should come from the maternal lines and the all male production from the YY technology. Therefore, TIL-GEN developed two female lines: “Fast” and “Strong”. TIL-GEN has carried out extended trials by crossing YY males with females from both lines. These trials have resulted in all natural male populations (OMT) with superior growth rates.


The tilapia industry faces the problem of the large difference between the growth rates of males and females, which can not be reduced by means of selective breeding. As shown on the table, males can grow to be twice as large as the females. As a result, "mixed-sex" tilapia producton is not economically viable..

The “mixed-sex” feed conversion ratio is much higher than that of all male populations. At least 95% of the population has to be male in order to produce tilapia in an economically viable way. To obtain all male populations for fattening, testosterone is used on a large scale for sex reversal during the first three weeks after hatching. Hormone Use: The use of testosterone for sex reversal has a strong negative effect upon the fish’s immune system. By using high efficiency maternal tilapia lines, it is possible to produce tilapia with less feed and less pollution of water sources. Apart from the YY technology, there is no other choice for the production of all male tilapia. In order to produce YY female, TIL-GEN has developed a “temperature treatment” to produce YY offspring. NO hormones are used. TIL-GEN is synonymous with sustainability.