Oreochromis mossambicus

The Mozambique tilapia (Oreochromis mossambicus) is an oreochromine cichlid fish native to southeastern Africa. Dull colored, the Mozambique tilapia often lives up to a decade in its native habitats. It is a popular fish for aquaculture. Due to human introductions, it is now found in many tropical and subtropical habitats around the globe, where it can become an invasive species because of its robust nature. These same features make it a good species for aquaculture because it readily adapts to new situations.

The Mozambique tilapia is native to inland and coastal waters in southeastern Africa, from the Zambezi basin in Mozambique, Malawi, Zambia and Zimbabwe to Bushman River in South Africa's Eastern Cape province. It is threatened in its home range by the introduced Nile tilapia. In addition to competing for the same resources, the two readily hybridize. This has already been documented from the Zambezi and Limpopo Rivers, and it is expected that pure Mozambique tilapia eventually will disappear from both. Otherwise it is a remarkably robust and fecund fish, readily adapting to available food sources and breeding under suboptimal conditions. Among others, it occurs in rivers, streams, canals, ponds, lakes, swamps and estuaries, although it typically avoids fast-flowing waters, waters at high altitudes and the open sea. It inhabits waters that range from 17 to 35 °C (63–95 °F).

The Mozambique tilapia is native to inland and coastal waters in southeastern Africa, from the Zambezi basin in Mozambique, Malawi, Zambia and Zimbabwe to Bushman River in South Africa's Eastern Cape province. It is threatened in its home range by the introduced Nile tilapia. In addition to competing for the same resources, the two readily hybridize. This has already been documented from the Zambezi and Limpopo Rivers, and it is expected that pure Mozambique tilapia eventually will disappear from both. Otherwise it is a remarkably robust and fecund fish, readily adapting to available food sources and breeding under suboptimal conditions. Among others, it occurs in rivers, streams, canals, ponds, lakes, swamps and estuaries, although it typically avoids fast-flowing waters, waters at high altitudes and the open sea. It inhabits waters that range from 17 to 35 °C (63–95 °F).

Mozambique tilapia are omnivorous. They can consume detritus, diatoms, phytoplankton, invertebrates, small fry and vegetation ranging from macroalgae to rooted plants. This broad diet helps the species thrive in diverse locations. Due to their robust nature, Mozambique tilapias often over-colonize the habitat around them, eventually becoming the most abundant species in a particular area. When over-crowding happens and resources get scarce, adults will sometimes cannibalize the young for more nutrients. Mozambique tilapia, like other fish such as Nile tilapia and trout, are opportunistic omnivores and will feed on algae, plant matter, organic particles, small invertebrates and other fish. Feeding patterns vary depending on which food source is the most abundant and the most accessible at the time. In captivity, Mozambique tilapias have been known to learn how to feed themselves using demand feeders. During commercial feeding, the fish may energetically jump out of the water for food.

Mozambique tilapias often travel in groups where a strict dominance hierarchy is maintained. Positions within the hierarchy correlate with territoriality, courtship rate, nest size, aggression, and hormone production. In terms of social structure, Mozambique tilapias engage in a system known as lek-breeding, where males establish territories with dominance hierarchies while females travel between them. Social hierarchies typically develop because of competition for limited resources including food, territories, or mates. During the breeding season, males cluster around certain territory, forming a dense aggregation in shallow water. This aggregation forms the basis of the lek through which the females preferentially choose their mates. Reproductive success by males within the lek is highly correlated to social status and dominance. In experiments with captive tilapias, evidence demonstrates the formation of linear hierarchies where higher-ranked males participate in significantly more agonistic interactions. Mozambique tilapias display more agonistic interactions towards fish that are farther apart in the hierarchy scale than they do towards individuals closer in rank. One hypothesis behind this action rests with the fact that aggressive actions are costly. In this context, members of this social system tend to avoid confrontations with neighboring ranks in order to conserve resources rather than engage in an unclear and risky fight. Instead, dominant individuals seek to bully subordinate tilapias both for an easy fight and to keep their rank.

In the first step in the reproductive cycle for Mozambique tilapia, males excavate a nest into which a female can lay her eggs. After the eggs are laid, the male fertilizes them. Then the female stores the eggs in her mouth until the fry hatch; this act is called mouthbrooding. One of the main reasons behind the aggressive actions of Mozambique tilapias is access to reproductive mates. The designation of Mozambique tilapias as an invasive species rests on their life-history traits: Tilapias exhibit high levels of parental care as well as the capacity to spawn multiple broods through an extended reproductive season, both contributing to their success in varying environments. In the lek system, males congregate and display themselves to attract females for matings. Thus, mating success is highly skewed towards dominant males, who tend to be larger, more aggressive, and more effective at defending territories. Dominant males also build larger nests for the spawn. During courtship rituals, acoustic communication is widely used by the males to attract females. Studies have shown that females are attracted to dominant males who produce lower peak frequencies as well as higher pulse rates. At the end of mating, males guard the nest while females take both the eggs and the sperm into their mouth. Due to this, Mozambique tilapias can occupy many niches during spawning since the young can be transported in the mouth. These proficient reproductive strategies may be the cause behind their invasive tendencies. Male Mozambique tilapias synchronize breeding behavior in terms of courtship activity and territoriality in order to take advantage of female spawning synchrony. One of the costs associated with this synchronization is the increase in competition among males, which are already high on the dominance hierarchy. As a result, different mating tactics have evolved in these species. Males may mimic females and sneak reproduction attempts when the dominant male is occupied. Likewise, another strategy for males is to exist as a floater, travelling between territories in an attempt to find a mate. Nevertheless, it is the dominant males who have the greatest reproductive advantage.

The native, wild-type Mozambique tilapia is laterally compressed, being deep bodied. It has long dorsal fins, the front part of which have spines. Native coloration is a dull greenish or yellowish, and weak banding may be seen. Adults reach up to 39 cm (15 in) in standard length and up to 1.1 kg (2.4 lb). It lives up to 11 years. Size and coloration may vary in captive and naturalized populations due to environmental and breeding pressures.

As with most species of tilapia, Mozambique tilapia have a high potential for hybridization. They are often crossbred with other tilapia species in aquaculture because purebred Mozambique tilapia don't grow as quickly and have a body shape poorly suited to cutting large fillets; these hybrids may or may not be reported as hybrid fish, often being listed as the wild species, Oreochromis mossambicus. Mozambique tilapia are hybridized because they naturally tolerate saltwater, a desirable trait in aquaculture, and the resultant offspring may inherit this trait. Also, hybrids between certain parent combinations (such as between Mozambique and Wami tilapia) result in offspring that are predominantly or entirely male. Male tilapia are preferred in aquaculture as they grow faster and have a more uniform adult size than females. The "Florida Red" tilapia is a popular commercial hybrid of Mozambique and blue tilapia.

The species is known by a number of common names in places where they were introduced, including: Blue kurper in South Africa. Mujair in Indonesia, the name derived from a Javanese breeder Moedjair. Daya in Pakistan Jesus fish in the Elim area of Jamaica, named for their habit of multiplying Tilapia negra (lit. black tilapia) in Colombia