FishConsultGroup's video: Gading of tilapia fry for sex reversal process

Because of the superiority of tilapia males over females in regard to growth rate, several scenarios are adopted towards the culture of all-male tilapia. Whether the use of male hormone (17-alpha methyl testosterone) is permitted or banned, its use is widely practiced in the sex reversal process. In order for the hormonal treatment to be highly effective, the treated fry should be at a very young age and hence the hormonal treatment covers the period of sexual un-differentiation that lasts 22 days for tilapia ending by all-male tilapia seeds that are targeted for the use in farming operations. While controlled reproduction through the collection and incubation of fertilized eggs allows knowing the age of hatched fry, and so the hormonal treatment is applied to known age of tilapia fry and so, if all elements of the sex reversal process are properly applied, a very high ratio of produced males is expected. In regard to the mass spawning that depends on the collection of fry, the age of fry cannot guarantee to be the optimum. Instead, the size of fry is used to indicate its age. Based on the scientific findings, the fry with a total length of 11-12 mm are suitable for the sex-reversal process. On the other hand, the effectiveness of the hormonal treatment on larger sizes produces questionable results. In order to have the optimum results of the grading of collected tilapia fry, a grader with a 2.5 mm opening (mesh) is recommended; the passed fry undergoes the hormonal treatment while retained fry could be used in different farming systems.