Tilapia fish have intrinsic biological characteristics that make them especially suitable for aquaculture. These characteristics are mainly: rapid growth, tolerance to a wide range of environmental factors (temperature, salinity, dissolved oxygen, etc.), resistance to diseases and stress, efficient feed conversion, early sexual maturation, high fecundity and tolerance to a wide range of foods. In addition to all these advantages, tilapia meat has good texture and flavor at affordable prices. All this gives it an essential role in the production of affordable protein.

This article focuses on and reviews the reproductive processes of tilapia, from sexual maturation to egg hatching, highlighting the factors that influence to improve each stage.

Introduction

Tilapia is one of the most widely farmed species in global aquaculture. Its ability to adapt to different environmental conditions and its rapid growth make it an ideal choice for aquaculture production. Efficient reproduction of tilapia is crucial for the sustainability of its production, as it allows maintaining a constant supply of fry for farming.

Sexual maturation

Tilapia reach sexual maturity between 6 and 8 months of age, although this period can vary depending on factors such as water temperature and food availability (Reyes-Trigueros et al., 2023). Sexual maturation is a complex process that involves physiological and hormonal changes in fish. During this stage, males develop secondary characteristics such as fin enlargement and changes in coloration, while females develop mature ovaries capable of producing viable eggs.

Under culture conditions, males can reach sexual maturity between four to six months, while females between three and five months and can occur below the commercial size (approximately 250 g) between 50 and 100 g (El-Sayed, 2016). Once sexually mature, females can spawn between 8 and 12 times a year, again depending on environmental characteristics (INAPESCA, 2018).

Reproductive behavior

The number, size and quantity of eggs that the female can spawn will depend on the size of the mother.

The reproductive behavior of tilapia is well documented. During courtship, males build nests on the bottom of the pond using materials such as sand and small stones. These nests serve as spawning sites where females (with cystovarian ovulation, i.e. the oocytes are deposited in the lumen of the ovary) deposit their eggs. Once the eggs are deposited, the males fertilize them externally (Reyes-Trigueros et al., 2023).

Table 1. Biometric and reproductive parameters. (Inaspesca, 2018)

Incubation and hatching

One of the most interesting aspects of tilapia reproduction is mouthbrooding. After fertilization, females collect fertilized eggs in their mouth and incubate them there until they hatch. This behavior, known as mouthbrooding, provides additional protection to the eggs against predators and adverse environmental conditions. Incubation lasts between 7 and 10 days, depending on water temperature (Reyes-Trigueros et al., 2023). During this period, females do not feed, demonstrating a high degree of parental investment.

The hatching rate, which refers to the ratio between fertilized and hatched eggs, is a relevant factor in calculating the potential of broodstock to produce viable eggs (Reyes-Trigueros et al., 2023).

Factors affecting reproduction

On a practical level, it is not advisable to underestimate the importance of environmental stimuli on tilapia reproduction, such as photoperiod, temperature, water quality and good nutrition.

Tilapia reproduction is influenced by several environmental and biological factors. Some of the most important factors are described below:

• Water temperature: The optimal temperature for tilapia reproduction is between 25°C and 30°C. Temperatures outside this range can negatively affect fertility and hatching rate (Reyes-Trigueros et al., 2023). For example, temperatures that are too low can slow down egg development, while temperatures that are too high can increase embryo mortality.
• Water quality: Parameters such as pH, dissolved oxygen concentration and water hardness are crucial for reproductive success (Navas J., 2009). An adequate pH, generally between 6.5 and 8.5, and optimal dissolved oxygen levels are essential for embryonic development and fry survival.
• Diet: A balanced, protein-rich diet improves fecundity and egg quality (Reyes-Trigueros et al., 2023). Well-fed females produce larger eggs with greater nutrient reserves, which increases the chances of fry survival, since they will initially feed directly from the sac.
• Population Density: Population density in culture ponds can also affect reproduction. High densities can increase stress and competition for resources, which can reduce fecundity and the reproductive success rate.

It should also be noted that fecundity and fertility, as well as the hatching rate, also depend on genetic characteristics.

Conclusions

Tilapia reproduction is a complex process influenced by multiple environmental and biological factors. Understanding these factors is essential to optimize aquaculture production of this species. Continued research in areas such as genetics, nutrition, and environmental management may provide new strategies to improve reproductive efficiency and sustainability of tilapia production.

References

• El-Sayed, A. (2016). Tilapia culture. CAB Int. Oxfordshire, UK. Online: https: / / shorten. link / zinHtLINAPESCA (2018). Tilapia aquaculture
• Navas, J. (2009). Fish reproduction: basic aspects and their applications in aquaculture. In: Scientific and technological publications of the Spanish Aquaculture Observatory Foundation.
• Reyes-Trigueros, L., Monroy-Dosta, M. C., Torres-Ochoa, E., & Cortés-Sánchez, A. J. (2023). Reproductive parameters in the production of tilapia fry Oreochromis niloticus: a review. La Granja: Journal of Life Sciences, 38(2), 124-137. https://doi.org/10.17163/lgr.n38.2023.09