Use of Dietary Phytochemicals as control for Excessive Breeding in Nile Tilapia (Oreochromis niloticus): A review

Human population has continued to increase unabatedly with its attendant demands on food in order to ease the difficulties of malnutrition and starvation. This continuous rise in population has clearly indicated that the conventional forms of livestock production and captured fisheries will not be sufficient to solve the problem of high protein demands. Aquaculture remains the best option that can bridge the wide gap between human protein demands and domestic production through the culture of fish species like Nile Tilapia (Oreochromis niloticus). Oreochromis niloticus is one of the most cultured finfish, due to its acceptability as food, fast growth, availability for farmers, ability to breed in captivity, resistance to diseases and harsh environmental conditions. Despite all these outstanding characteristics, there is still high level of apathy in commercial production of Nile Tilapia, due to its precocious maturity and uncontrolled breeding, which results in overpopulation of ponds, stunted growth and low commercial value. To mitigate this challenge, the use of synthetic hormones such as 17α-methyl testosterone has been developed to masculinize female tilapia present in a pond, thereby allowing the production of marketable sized fish since the male grows faster than the female. Though, the use of synthetic hormones has helped in some ways, but the negative effects have necessitated farmers to seek alternatives that are environmental friendly and safe for consumers. Dietary phytochemicals have been established to be good alternatives and their use is now gaining global acceptance. Dietary phytochemicals are bioactive compounds commonly found in plant-based diets such as fruits, vegetables, grains and teas. Dietary phytochemicals when administered to newly hatched tilapia species, influences the undifferentiated gonadal tissue of generic females to develop testicular tissue, thus functioning reproductively as males. Some of these phytochemicals such as Flavonoids, Saponins, Phenolics and Alkaloids are found in plants like Carica papaya seeds, Azadirachta indica, and Mucuna pruriens. The usefulness of these phytochemicals is based on their ability to influence sex reversal in Oreochromis niloticus, cost effect, easily accessible especially by small scale fish farmers, simple to apply, and being safe for both human and the environment since they are more biodegradable than synthetic hormones.