Monosex production of tilapia, Oreochromis niloticus using different doses of 17α-methyltestosterone with respect to the degree of sex stability after one year of treatment

Effect of Passiflora incarnata (L) extract on gonadal maturation in young tilapia (Oreochromis sp.)

“…The use of herbal extracts as sex reversal inducers in fish has a variable efficiency percentage, most often no more than 80%, depending on the plant used, concentration of active ingredients, the species studied, and the developmental phase of the organism during application (Ghosal & Chakraborty, 2014;Ghosal et al, 2016). This places the alternative at a disadvantage in comparison to the 97% sex reversal of the conventional method (El-Greisy & El-Gamal, 2012). In search for alternatives to maintain reproductive control, studies have been carried out such as those by Jegede (2010) and Kushwaha (2013) to evaluate the effect of Hibiscus rosa-sinensis (2.0 g kg -1 feed) and Aloe vera extract (4.0 g kg -1 feed), respectively, on the development and gonadal maturation of Oreochromis niloticus.…”

“…The most commonly used technique for the creation of monosex cultures is known as sex reversal, which consists in the oral administration of the synthetic hormone 17-α-methyltestosterone (17-α-MT) incorporated into feed and supplied during the first days of life after yolk sac assimilation (7 to 10 days after hatching). During this period the gonads are stimulated to develop into testes both in males and genotype females due to the masculinizing action of this synthetic hormone (Green & Teichert-Coddington, 2000;El-Greisy & El-Gamal, 2012). In the first days of fish life the gonads are in a period of non-differentiation (bipotential) and are susceptible to external influences that can alter the normal process of sexual differentiation (Devlin & Nagahama, 2002).…”

“…An average adult male has the ability to remove up to 10 mg of androgen per day. This guarantees the elimination of any residual 17-α-MT that could be found in the muscle after the clearance period recommended by the FDA, ensuring the safety of the product offered on the market (Green & TeichertCoddington, 2000;El-Greisy & El-Gamal, 2012;Megbowon & Mojekwu, 2014;Mlalila et al, 2015). Despite the effectiveness and safety of this technique, in the last decades' herbal extracts have been proposed for use as active agents to control reproduction in the cultivation of tilapia, in order to find more economically accessible alternatives for aquaculture development (Gabriel et al, 2015).…”

“…Studies performed over the last decades have provided insight into these aspects and assisted in their integration into cultivation practices (Das et al, 2012). The success of tilapia culture results from the excellent adaptation of this group of fishes to industrial culture conditions but their reproductive precocity requires control measures to prevent the diversion of energy from muscle production to reproduction (Das et al, 2012;El-Greisy & El-Gamal, 2012). Some of the most frequently used reproductive __________________ Corresponding editor: Cesar Lodeiros control measures involve the creation of monosex cultures through sex reversal, interspecific hybridization, and manual sex selection.…”

The sex ratio and testosterone levels in tilapia immersed in different doses of 17α-methyltestosterone

“…This may be due to the rearing condition in aquarium, which was not sufficient for optimal fish growth.. In contrast, Greisy and Gamal (2012) found that MT hormone orally administered to fish in the form of feed at 40 mg/kg demonstrates higher growth performance, whereas Rahman & Christian (2007) reported that the presence of testosterone hormones in feed could lead to high muscle mass growth.…”